Using extensive interviews with colleagues, opponents and friends and archival footage, the film follows the principal's influential career, working with Karl Rove, Ronald Reagan, Roger Stone, Paul Manafort and others, culminating in the defining Bush 1988 presidential campaign and its aftermath.

Nostalgia for the Light opens with a view of a telescope and images of the Moon. The narrator, Patricio Guzmán, describes how he came to love astronomy and begins to remember his childhood during which “only the present moment existed.” Soon, Chile became the center of the world as astronomers and scientists flocked to Chile to observe the universe through the thin and clear skies. We next see Guzmán walking in the Atacama Desert, a place with absolutely no moisture, so much so that it resembles the surface of Mars. This desert, and its abundance of history, becomes the focus of the documentary. Because of how dry it is, the desert hosts the untouched remains of fish, mollusks, Indian carvings, and even mummified humans. Astronomer Gaspar Galaz is introduced and comments on how astronomy is a way to look into the past to understand our origins. It is generally a science seeking answer, but, in the process, creates more questions to answer. He comments that science in general, like astronomy and geology, is a look into the past; even sitting there having this interview, he comments, is a conversation in the past because of the millionths of a second light takes to travel and be processed. Lautaro Núñez relates astronomer's endeavors to his own; archeologists and astronomers have to recreate the past while in the present by using only a few traces. The documentary then shifts into Chile's recent past dealing with Pinochet and his dictatorship. Luís Henríquez, a survivor from the Chacabuco concentration camp, describes how a group of about 20, led by a Doctor Alvarez (who was knowledgeable in astronomy), were taught theory during the day and learned how to identify constellations at night. They learned how to create a device that helped them track the constellations, and while they studied the cosmos they “all had a feeling of great freedom,” as Henríquez describes it. The military, however, quickly banned these lessons because they believed the prisoners could escape using the constellations. Miguel Lawner, similarly, was a prisoner who survived the concentration camp. He is referred to as the “architect” in the movie because he was able to memorize and then later recreate the environment the prisoners lived in. Miguel would measure buildings and the grounds with footsteps and would then draw a scaled version of the concentration camps with those measurements. He would rip his drawings up and hide them at night, in case of a raid, and then flush them down the latrines in the morning. The narrator concludes that he and his wife Anita are a metaphor for Chile: Henríquez remembers what happened in the past, while Anita, who has Alzheimer's disease, is forgetting. Valentina Rodríguez talks about how her grandparents were detained and threatened to give up the location of her parents. After their captors threatened to hurt Valentina, her grandparents complied and her parents were taken away. However, Valentina acknowledges that she and her parents all belong to the recyclable matter of the universe, which brings peace to her. She has a son, who she knows will not have to suffer dictatorial violence like his past generations. This idea leaves her strong and optimistic. Guzmán ends the documentary affirming the value of memory because, as he states, “those who have a memory are able to live in the fragile present moments. Those who have none don't live anywhere.”