Sun Ra, who has been reported lost since his European tour in June 1969, lands on a new planet in outer space with his crew, known as "the Arkestra", and decides to settle African Americans on this planet. The medium of transportation he chooses for this resettlement is music. He travels back in time and returns to the Chicago strip club where he used to play piano with the name "Sonny Ray" in 1943, where he confronts the Overseer (Ray Johnson), a pimp -overlord, and they agree on a game of cards for the fate of the Black race. In present time (the early 1970s), Ra disembarks from his spaceship in Oakland and tries to spread word of his plans. He meets with young African Americans at an Oakland youth centre and opens an "Outer Space Employment Agency" to recruit people eager to move to the planet. He also agrees with Jimmy Fey (Christopher Brooks) — an employee of the Overseer — to arrange radio interviews, a record album, and eventually a concert that will help him dictate his message. As the card game between Ra and the Overseer is played, and it becomes clear that the Overseer is winning, Ra's plans to recruit local black youth for his new utopian space colony suffer setbacks. Many of them are suspicious of Ra, accusing him of faking his outer-spatial origin as a gimmick to boost his record sales. He is kidnapped by a team of white NASA scientists who threaten him with violence, desperate to learn the secrets to his space-travel technology. As Ra's concert rapidly approaches, he is saved by three local teenagers, who escort him to the music hall just in time. At the concert, as the Arkestra play their signature free jazz, the NASA scientists appear and attempt to assassinate Ra with a pistol. One of the teenagers jumps in front of the bullet, saving Ra's life, and as he is bleeding out on the stage, Sun Ra waves his hand and the teenager, his friends, and Ra himself all disappear from the music hall. One by one, black people across Oakland vanish into thin air and reappear on Ra's spaceship. Jimmy Fey resists leaving Earth on Ra's spaceship, but Ra doesn't let Fey leave; Ra takes Fey's "black parts" with him onto the spaceship, leaving his "white parts" behind on Earth. Fey, now acting white, leaves the Overseer, who loses the duel. As Ra's spaceship launches off into the cosmos and music begins playing, a montage implies that Earth is destroyed in its wake.

To relieve his boredom, Emperor Ming the Merciless of the planet Mongo begins Earth 's destruction by remotely causing natural disasters. On Earth, football star Gregory "Flash" Gordon boards a small plane and meets travel agent Dale Arden. Mid-flight, the cockpit is hit by a meteor and the pilots die. Flash takes control and manages to crash land into a greenhouse owned by former NASA scientist, Dr. Hans Zarkov. Zarkov believes that the disasters are being caused by extraterrestrials pushing the Moon towards Earth. He has secretly constructed a spacecraft to investigate the attacks. Unable to do it alone, Zarkov lures Flash and Dale aboard. He flies with them to Mongo, where they are captured by Ming's troops. After looking at the trio, Ming is smitten with Dale and orders Flash executed. At the last minute, Ming's daughter, Princess Aura, saves Flash, with whom she fell in love at first sight. While they escape, Zarkov is brainwashed by Klytus, the head of the secret police. Aura and Flash flee to Arboria, kingdom of Prince Barin. Locked in Ming's bedchamber, Dale escapes, and Zarkov is sent to intercept her. However, Zarkov reveals he resisted the brainwashing, and escapes Mingo City with Dale. They are quickly captured by Prince Vultan 's hawkmen and taken to Sky City. Aura and Flash arrive at Arboria. Aura asks the Prince to keep Flash safe. A distrustful Barin, in love with Aura, agrees not to kill Flash, but then forces him to play a deadly game of chance. With the odds stacked against him, Flash uses this opportunity to escape. Barin follows him, and they are both captured by the hawkmen. Aura returns and is taken prisoner and tortured by Klytus and General Kala for her treason. Meanwhile, Ming prepares his wedding to Dale. Flash and Barin are taken to Sky City, where Flash and Dale are briefly reunited. Flash is forced to fight Barin in a death match. However, Flash instead saves Barin's life, causing Barin to join him. Klytus arrives, and Flash and Barin kill him. Knowing this will bring retribution, Vultan and the hawkmen evacuate, leaving Barin, Flash, Dale and Zarkov behind. Ming's ship arrives and captures Barin, Zarkov and Dale. Impressed with Flash, Ming offers him lordship over Earth in exchange for loyalty. Flash refuses and Ming gives the order to destroy Vultan's kingdom along with Flash. Finding a rocket cycle, Flash escapes before Sky City is destroyed. Flash contacts Vultan, and they plot an attack on Mingo City. To defend the city, General Kala dispatches the war rocket Ajax, which is quickly seized by the hawkmen. Meanwhile, Princess Aura overpowers her guard and frees Barin and Zarkov from the execution chamber. Flash and the hawkmen attack Mingo City in Ajax and Kala activates the defenses as Ming's and Dale's wedding begins. Mingo City's lightning field can only be penetrated by flying Ajax into it at a suicidal speed. Flash volunteers to stay at the helm to ensure success and enable the hawkmen to invade the city. Barin and Zarkov enter the control room and confront Kala. In the ensuing fight, Barin shoots and kills her. After fighting through Ming's guards, Barin also manages to deactivate the lightning field before Ajax hits it. Flash flies the rocket ship into the city's wedding hall and impales Ming. Flash offers to spare his life if he stops the attack on Earth. Ming refuses and attempts to use his power ring on Flash, but it falters and nothing happens. He then aims the ring at himself and is seemingly vaporized by its remaining power. A victory celebration ensues. Barin and Aura become the new leaders in Ming's place. Barin names Vultan the general of their armies. Flash, Dale and Zarkov discuss returning to Earth. Zarkov says he does not know how they will get back, but they will try. Meanwhile, Ming's ring is picked up by an unseen person. Ming's evil laugh is heard closely after.

In 2018, Jonathan E. is the team captain and veteran star of the Houston Rollerball team. Mr. Bartholomew, chairman of the Energy Corporation — one of a series of corporations that now govern society — and team sponsor, offers Jonathan a lavish retirement package if he will announce his retirement during an upcoming television special detailing his career. Jonathan refuses, and requests to see his former wife Ella, who had been taken from him some years earlier by a corporate executive who wanted her for himself. Jonathan goes to a library, where he finds that all books have been digitized and edited to suit the corporations, and are now stored on supercomputers at large protected corporate locations. Jonathan's friend and former coach Cletus, now an Energy executive, warns him that the Executive Committee is afraid of him, though he cannot find out why. Rollerball soon degrades into senseless violence as the rules are changed to force Jonathan out. The semi-final match between Houston and Tokyo is played with no penalties and limited substitutions in the hope Jonathan will be injured and forced out. The brutality of the match kills several players on both teams and leaves Jonathan's best friend and teammate Moonpie brain-dead, though Houston wins the game. In a teleconference, the Executive Committee decides that the final match will be played with no penalties, no substitutions, and no time limit in the hope that Jonathan will be killed during the game. Jonathan's popularity and longevity as a player threaten the underlying agenda of Rollerball: to demonstrate the futility of individualism. Jonathan makes his way to Geneva to access the world's repository of all human knowledge, a central supercomputer known as "Zero," only to find its memory corrupted. Afterwards, Jonathan receives a visit from his former wife Ella, who has been sent to convince him to retire and to make it clear that the coming game will be "to the death". Jonathan realizes his wife's visit was set up by the Executives, and erases a long-cherished movie of the two of them, stating, "I just wanted you on my side". Jonathan decides that despite the dangers, he will play in the championship game against New York. The final match devolves into a brutal gladiatorial fight. Jonathan is soon the only Houston player left on the track, while a skater and a biker remain from New York. After a violent struggle in front of Mr. Bartholomew's box, Jonathan kills the skater and takes the ball. The biker charges, and Jonathan knocks him off the bike and pins him down. Refusing to kill his fallen opponent, Jonathan gets to his feet and makes his way to the goal, slamming the ball home and scoring the game's only point. Jonathan then takes a victory lap as the crowd chants his name, first softly, then slowly rising to a roar while Mr. Bartholomew hastily exits the stands.

Billionaire New Yorker Damian Hale is diagnosed with terminal cancer. He finds a business card directing him to Professor Albright, who informs him about a medical procedure called "shedding", in which one's consciousness is transferred into a new body. Damian agrees to the procedure and follows Albright's instructions to stage his own public death. Albright then transfers him into a new, younger body, and prescribes medication to alleviate the vivid hallucinations which he claims are side effects of the procedure. Damian starts a new life in New Orleans under the incognito name of Edward Kidner and is quickly befriended by his neighbor Anton. He later forgets to take his medicine and has hallucinations of a woman and child. Damian (as Edward) questions Albright, who dismisses it, but accidentally mentions details of the hallucinations that Damian had not disclosed. Albright then arranges for Damian to take a vacation in Hawaii, but Damian, convinced the hallucinations are a real memory, identifies a landmark he saw in his vision and heads to a farmhouse outside of St. Louis. There, he finds the woman, Madeline, who reacts to him as her apparently deceased husband Mark. Damian plays along as Mark, though he is shocked to learn that Mark may have sold himself to Albright, in order to pay for their daughter Anna's life-saving treatment. Damian and Madeline are suddenly attacked by Albright's men, including Anton. Damian fatally wounds Anton and kills his accomplices, then flees with Madeline to pick up Anna from school. At a nearby motel, Damian then uses a laptop to research additional details regarding "shedding", and discovers that a man named Dr. Francis Jensen, now deceased, was the pioneer researcher in the field of transhumanism. In a video, Damian notices a tic Jensen shares with Albright, then sees Albright sitting next to Jensen, deducing that Jensen may have shed his consciousness into Albright's body. Damian then finds Jensen's wife, Phyllis, in a nursing home, but she has Alzheimer's and remembers nothing. Damian lures Jensen (Albright) to the facility, where he reveals that the pills are meant to fully eliminate the original personalities of the bodies used in the shedding procedure, telling Damian that without the pills, Damian's consciousness will die, and Mark's will re-emerge. Jensen later escapes when more killers arrive. Damian is almost overpowered, but Madeline wounds the attacker, who proves to be Anton in a new body. Anton reveals that he has shed multiple times. While Damian confiscates Anton's pills, Anton taunts Madeline to ask her "husband" why he cannot answer personal questions about their life. Madeline then confronts "Mark" over his lack of knowledge of their personal details, causing Damian to reveal the entire story. He takes her and Anna to his old friend Martin O'Neill and convinces Martin to arrange for Madeline and Anna to flee to the Caribbean. When he and Madeline discover Anna playing with Martin's previously deceased child Tony, Martin admits that he allowed Tony to also use shedding and that Jensen's men are coming. Damian then reveals shedding's secret to Martin, who reacts in shock and disgust. Damian distracts Jensen's men while Martin helps the others to flee. Damian again fatally injures Anton, but the other thugs realize that Damian is alone and turn back, recapturing Madeline and Anna. Damian then purposely stops taking his medicine to experience more of Mark's memories, which reveal that Jensen has a lab in an abandoned warehouse. Jensen captures him and starts to shed Anton into Mark's body. Damian, remembering that metal interferes with the process, hides a bullet casing in his mouth, causing the Shedding Machine to malfunction, preventing the transfer of Anton's consciousness. Masquerading as Anton, Damian then rescues the others. Although Jensen tries to claim that Damian needs him to survive, Martin was able to reverse-engineer the pills and give Damian the formula, allowing Damian to safely torch Jensen to death with a flamethrower. After killing Jensen, he has Martin complete Madeline and Anna's escape to the Caribbean. Damian later visits his estranged daughter Claire but does not reveal his presence inside Mark, simply giving her a letter that reconciles Claire with her father. Damian then travels to the Caribbean and fully stops taking his medicine. The real Mark then slowly re-emerges and finds a video message from Damian thanking him for the time that he gave to him. The story concludes with Mark finally reuniting with his family.

A group of 30 scientists travel from Earth to a nearly-identical alien planet that is culturally and technologically centuries behind. The inhabitants of this planet have brutally suppressed a renaissance movement, murdering anybody they consider to be an intellectual, and thus the planet is stuck in the middle ages. Anton, one of the scientists from Earth, is sent to infiltrate the local populace of the Kingdom of Arkanar and help them progress as a society, although he is forbidden from getting involved with local politics or forcibly interfering with the advancement of technology or culture. He assumes the identity of Don Rumata, a nobleman who resides in a large castle surrounded by poverty. There, he lives with Ari, a young woman whom he has taken as his bride, and the juvenile prince of Arkanar. Rumata's presence divides local opinion; some treat him as a God, others despise him. Don Rumata tasks himself with finding Budakh, a doctor who has been kidnapped by Don Reba, the tyrannical prime minister of Arkanar. Reba's militia, referred to as "the Greys", are responsible for the murder of many intellectuals, including scientists and writers. During his travels, Rumata witnesses the backward ways of the locals and becomes increasingly frustrated with them. Slavery is rife, and the influence of Reba's Greys turns Arkanar into a police state. One night, while guarding the prince, the Greys besiege the castle and attempt to arrest Rumata. Rumata attempts to escape, but is ambushed and taken before his rival, Don Reba. Reba does not trust Rumata and claims he is an impostor. Rumata reasons with Reba and is freed, along with Budakh. Later, Rumata meets his friend Pampa, a drunken and washed-up baron. Rumata teaches Pampa his famed signature sword-fighting technique. When Rumata returns to his castle, he finds the local area has been taken over by religious zealots in his absence, called "the Blacks", who prove to be just as oppressive as the Greys. Rumata discovers that Budakh is an impostor, and that the real Budakh is still imprisoned at Don Reba's castle. He returns to Reba on peaceful terms and searches the sewers of the castle for Budakh. He eventually finds him, as well as Baron Pampa, who has been tortured by Reba's men. Rumata, Pampa and Budakh escape Reba's castle, but Pampa is shot by archers and killed. Upon returning to his village, Rumata becomes annoyed when he discovers that Budakh, apparently a great doctor and intellectual, is actually a bumbling fool who is unable to even urinate properly. He sends Budakh away and retires to his castle. The next day, the Greys attack the castle and kill Ari. Enraged, Rumata butchers their leader. The next morning, a group of travelers investigates the aftermath of the ensuing battle, which has cost the lives of most of Arkanar's inhabitants. Among the dead civilians and soldiers, they find a lone survivor, Don Rumata. The leader of the travelers, another incognito scientist from Earth, offers to take Rumata back to Earth, but Rumata refuses. He instead gives the fellow scientist advice—that it is "hard to be a God". Months later, during the winter, Rumata is shown traveling away from Arkanar.

A case study demonstrates how individuals with lower IQ scores and incomes reproduce at greater rates than the more affluent and intelligent, reducing future humanity's average intelligence. In 2005, US Army librarian Joe Bauers is selected for a government suspended animation experiment as the most average individual in the armed forces. Lacking a suitable female candidate, the military hires a prostitute, Rita, by dismissing charges against her and paying off her pimp, Upgrayedd. A scandal involving the officer overseeing the initiative and Upgrayedd forces the closure of the military base under which Joe and Rita were placed in hibernation, suspending the project indefinitely. Over the next five hundred years, average intelligence decreases. As a result, infrastructure deteriorates, low comedy and vulgarity define culture, and consumerism is left unfettered. Five hundred years later, a garbage avalanche disturbs Joe and Rita's hibernation chambers. Joe awakens in Frito Pendejo's apartment in previously occupied DC. Asking for help, he is laughed at by the residents, who speak a mixture of "hillbilly, Valley Girl, inner-city slang, and various grunts." He enters a hospital, believing the army administered hallucinogenic drugs to him. Joe realizes the year upon reading a magazine and his hospital bill, but he is arrested at Carl's Jr. for not having a bar code tattoo and being unable to pay his bill. Joe is sent to trial; Frito represents him but alleges that he destroyed his apartment. The judge perceives Joe’s accent to have a homosexual demeanor, finding him guilty and sentencing him to prison. Rita resumes her job as a prostitute. Joe is sent to a correctional facility, where a faulty ID machine registers his name as "Not Sure" and takes a simplified aptitude test. He escapes from prison after deceiving a guard by saying he had served his sentence and was scheduled for release. Joe visits Frito, who agrees to guide him to a time machine —located within a large Costco store—after Joe promises to create a savings account in Frito's name when he returns to the 21st century, earning him billions in compound interest. Rita, Joe, and Frito enter the store, but Joe is arrested after his bar code is scanned. He is taken to the White House and appointed secretary of the interior by President Dwayne Elizondo Mountain Dew Herbert Camacho due to extraordinary performance on the aptitude test. In an address, Camacho states that Joe will resolve unfruitful crop yields, dust storms, and a stagnant economy, among other issues, within a week or face imprisonment. Joe and Rita visit a crop field. Frito gives him a useless map to the time machine. Joe discovers that the country's crops are being watered with Brawndo, a sports drink whose parent company owns the FDA, the HHS, and the FCC; the concentration of electrolytes in Brawndo has destroyed natural topsoil, causing dust storms. Despite opposition to his plan in the form of circular reasoning from the Cabinet, Joe convinces Camacho to use water instead of Brawndo in irrigation. Consequently, Brawndo stocks severely depreciate, leaving half the country's citizens unemployed and Brawndo filing for bankruptcy, inciting riots as immediate improvement to the crops did not materialize. At the Extreme Court, Joe is sentenced to public execution in a monster truck demolition derby against undefeated rehabilitation officer Beef Supreme. Rita and Frito discover that Joe's reintroduction of water to the soil allowed crops to grow. Rita pays a cameraman to broadcast the crops on the stadium's Jumbotron, prompting Camacho to grant Joe a presidential pardon. After discovering that the time machine is just an amusement ride, Joe becomes president and marries Rita, with whom he has "the three smartest kids in the world". Frito is appointed as the vice-president, and with 8 wives, he ultimately begets "32 of the dumbest children to ever walk on Earth". The narrator states that while Joe did not single-handedly save mankind, he did set in motion the chain of events that eventually undid humanity's "dumbing-down".

Jack Hall, a paleoclimatologist for the NOAA, drills for ice-core samples in the Larsen Ice Shelf with his colleagues Frank and Jason. A large portion of the ice shelf splits away, but they manage to escape. At a United Nations conference on global warming in New Delhi, Jack shares his theory that climate change could lead to a new ice age through the disruption of the North Atlantic Current. United States vice president Raymond Becker is dismissive of Jack's research, but Professor Terry Rapson, a Scottish oceanographer, befriends him over their shared concerns. Tokyo is struck by a giant hailstorm, and astronauts from the International Space Station spot three gigantic superstorms above Canada, Europe, and Siberia. Rapson's team notice severe temperature drops from multiple buoys in the North Atlantic, providing evidence for Jack's theory and that a climate shift may already be occurring. Remnants of a hurricane spawn a destructive tornado outbreak over the L.A. Basin. Three helicopters sent to rescue the British royal family from Balmoral Castle crash in Scotland after they fly through the eye of the European superstorm. Jack and Rapson's teams build a forecast model that predicts that the climate shift will occur in 6–8 weeks (later revised to 7–10 days). Rapson shares with Jack that siphoned air from the upper troposphere will flash freeze anything caught in the eye of a cyclone with temperatures below −150 degrees Fahrenheit (−101 degrees Celsius), which caused the royal family helicopter crashes by freezing the fuel on board. In New York City, Jack's son Sam, along with his friends Brian and Laura, participate in an academic decathlon, where they befriend JD. The North American superstorm creates strong winds and rain that flood Manhattan. All transportation halts, stranding the city's population. While helping to rescue two French-speaking tourists, Laura cuts her leg. A massive storm surge inundates the city, forcing Sam's group to seek shelter at the New York Public Library. Sam contacts Jack and his mother Lucy, a pediatrician, through a working payphone. Jack warns Sam of the impending superstorm, urges him to stay inside and warm, promising to rescue him. Rapson and his team succumb to the European storm. Lucy remains in her hospital, caring for bedridden patients, where the authorities eventually rescue them. Per Jack's suggestion, President Blake orders the populations of the southern states to be evacuated to Mexico, while instructing those in the northern areas to shelter-in-place. Jack, Jason, and Frank depart by snowshoe to NYC. While trekking across Pennsylvania, Frank falls through the skylight of a mall covered in snow, only stopped by his tether to Jack and Jason. When more of the skylight begins to crack, he sacrifices himself by cutting the tether. In the library, most survivors decide to move south on the frozen floodwater, despite Sam's warnings. In Mexico, Becker learns that Blake's motorcade perished in the superstorm and that he is now President. Laura develops sepsis from her injury, leading Sam, Brian, and JD to scour an abandoned Russian cargo ship that drifted into the city before the water froze for medical supplies. After finding penicillin, they encounter a pack of escaped wolves from the Central Park Zoo. The boys fight the wolves and return to the library before the eye of the North American superstorm passes over and freezes Manhattan. Jack and Jason barely escape the eye by taking shelter in an abandoned restaurant. Days later, the superstorms dissipate. Jack and Jason reach the library, finding Sam's group alive. Jack sends a radio message to US forces who arrive by helicopter. While being evacuated, other groups of survivors emerge. In his first address as president, Becker apologizes for his ignorance and shares the news of the New York survivors and further rescue missions being carried out. On the International Space Station, astronauts look down in awe at the ice sheets covering much of the Northern Hemisphere and remark that the air has never looked so clear.

The film's plot is centered on an engineer Jim Ripple who invents universal robots to help workers, being himself from a workers' family. He theorizes that cheap production will make all goods so cheap that Capitalism will fall. The workers do not share his view and his family considers him a traitor. A key element of his invention is a high-capacity capacitor that powers the robots. The government becomes interested in the invention because the robots can be used as a weapon as well. Ripple is given a top secret factory and funding so that he can produce robots. The robots are not autonomous or intelligent, and controlled either by radio or by sound, for which purpose Ripple uses a saxophone. When drunk he even makes the robots dance. At a day of a universal workers' strike, the administration of a factory where the Ripple's brother works, located in the same town where the robot producing plant is located, replaces workers with robots. A workers' delegation visits the factory to see that there are no strike breakers, and finds that actually it is the robots who do the work. The meeting ends with an accident when Ripple tries to show the abilities of a robot to the workers; in an accident, one of the workers dies. This sparks a conflict between workers and the plant administration assisted by the military. The military decides to use robots against the workers as a weapon. The robots are commanded by an officer sitting in a tank using a radio remote control device. Trying to prevent the hostilities Ripple tries to stop the robots with a saxophone, but he is unsuccessful and is killed. Finally the workers gain control over the robots with their own remote control device, which they had covertly assembled before, making necessary measurements on the robot assembling factory and researching the Ripple's prototype robot "Micron", whom he left damaged at his home.

Quarantined in a Tokyo mental hospital, a psychology professor named Kenji Murai is visited by a group of doctors asking him about the events that led him there. Murai proceeds to explain how, despite only two of his party being dead, he was the only one to be rescued. He then relates the story of his band of day trippers on a yacht: Murai, wealthy industrialist Masafumi Kasai (the owner of the yacht), salaryman skipper Naoyuki Sakuda, his shipmate assistant Senzō Koyama, celebrity writer Etsurō Yoshida, professional singer Mami Sekiguchi, and student Akiko Sōma. A sudden storm causes the yacht to nearly capsize. Though the boat remains upright, it sustains severe damage during the storm and drifts uncontrollably. The group arrive at a seemingly deserted island and begin to explore. They come across ponds full of fresh rainwater and a forest populated by unusually-large mushrooms. As they cross the island, they come upon a wrecked ship on the shore whose sails are rotted and its interior is covered with a mysterious mold. Murai, after reading the ship's log, warns them not to eat the mushrooms because they might be poisonous since the former crew had hallucinations after eating them. Finding that the mold is killed by cleaning products, they work to clear it from the ship. In doing so, they begin to suspect that the ship was connected to nuclear tests conducted in the vicinity of the island, with the resultant fallout forcing a bizarre mutation on various organisms native to the surrounding area, including the mushrooms. As the days pass, the group grows restless as their supply of food stores starts to run low. Kasai refuses to help find a way off the island and insists on living in the captain's quarters alone. One night, as Kasai is raiding the food stores, he is attacked by a grotesque-looking man who promptly disappears after encountering the group. A drunk Yoshida decides to try eating the mushrooms for their hallucinogenic properties. After scuffling with Koyama over Mami, Yoshida pulls a gun and declares his intent to have his way with the women after murdering the others (accepting that if the mushrooms do turn him into a monster, then there will be no consequences for his actions). Subdued by the others, Yoshida is locked in the captain's quarters, ironically ousting Kasai. Kasai tries to convince Naoyuki to abscond together with the food and repaired yacht. Naoyuki violently rebukes this notion, but an unstated amount of time later hogties Kasai and flees with all the gathered food (including Koyama's secret stash that they had been hoarding to extort money from Kasai). Faced with this dire prospect, Mami frees Yoshida and they attempt to take over the ship, shooting and killing Senzō in the process. Murai and Kasai manage to take the gun from Yoshida and force the two off the ship. Some time later, Kasai is confronted by Mami, who entices him to follow her into the forest and eat the mushrooms. Perpetual rainfall has caused wild fungal growth, and Kasai realizes that those who have been eating the mushrooms have turned into humanoid mushroom creatures themselves. The mushrooms are delicious and cannot be resisted after the first bite. Kasai eats the mushrooms, hallucinates scenes of Tokyo nightlife, and falls to his knees amongst the creatures. Murai finds the yacht adrift and swims out towards it. He finds a note left behind by Naoyuki listing the names of those on the island as dead and how, having now run out of food and energy, he has decided to jump into the sea. Murai draws a large X over the note. Others who have turned into mushroom creatures attack Akiko and Murai. They are separated and Akiko is kidnapped. As Murai tracks her down, he discovers that she has been fed mushrooms and is under their influence along with Mami, Yoshida, and Kasai. Murai attempts to rescue Akiko, but he is overwhelmed by the mushroom creatures and flees without her, making his way onto the yacht and escaping the island. Several days pass later, Murai is finally rescued. As he waits in the hospital, he begins to wonder if he should have stayed with Akiko on the island. His face is revealed to show signs of being infected with fungal growths. Murai states after that it did not matter whether he stayed or not, but he would have been happier there with Akiko. The screen fades as Murai notes that humans are not much different from the mushroom creatures.

After the town of Kaihoro's entire population disappear, the Astro Investigation and Defence Service (AIDS) sends their agents Derek, Frank, Ozzy, and Barry to investigate. They find the town overrun by man-eating aliens disguised as humans in blue shirts. Barry kills one of the aliens and is attacked by others. After Derek notifies Frank and Ozzy, he begins torturing Robert, an alien they caught earlier. Robert's screaming attracts a number of aliens. Derek kills the would-be rescuers, but he is attacked by Robert and falls off a cliff ledge, to his presumed death. Meanwhile, charity collector Giles passes through Kaihoro. He escapes Robert's attack and comes to nearby house for help, only to get captured by another alien. Giles later wakes up in a tub of water filled with vegetables and is told he is about to be cooked and eaten. Derek wakes up in a seagull 's nest with a hole in his head, so he uses a hat to keep his brains from leaking out. That night, Frank, Ozzy, and Barry infiltrate the aliens' house and find a room filled with bloody cardboard boxes, likely containing the corpses of former Kaihoro residents. They kill an alien, and Frank wears its shirt to infiltrate their meeting. He learns that the victims have been harvested for food and hears of their recent hostage, Giles. The alien later dines on Robert's vomit, and the disguised (and disgusted) Frank has to follow suit. He escapes and tells the others of the plan. They save Giles as the aliens sleep. At sunrise, they try to leave but are attacked by the aliens, and a gunfight ensues. Derek emerges and joins the fight, using his belt as a headband when the hat is shot off. He grabs a chainsaw from the boot of his car and heads for the aliens' house. As the group leaves with Giles, the alien leader (Lord Crumb) and his followers morph into their true form and follow. Ozzy uses a rocket launcher to explode Frank's car, which has been overrun by aliens. Frank and Ozzy hunt for Lord Crumb and kill many aliens along the way. Meanwhile, Derek kills an alien with his chainsaw and replaces the missing parts of his brain with its brain. An alien prepares to shoot Frank and Ozzy, but it is beheaded by Derek. Frank and Ozzy are shocked to see him alive, and see he has lost his mind. After they escape the house, Lord Crumb shoots Ozzy in the leg and Frank fires his rocket launcher at the leader, but misses. Lord Crumb knocks out Derek and the house transforms into a giant spaceship and blasts off into space. On board, Derek looks out the window to see Earth. He ambushes Crumb and kills the alien with his chainsaw. He proclaims war on the alien, then puts on the alien leader's skin and laughs maniacally as he rockets towards the alien planet. Back on Earth, the survivors drive away in Derek's car.