The film follows the attempts of aging Nazi hunter Ezra Lieberman (Sir Laurence Olivier) to discover and thwart a plan by surviving Nazi Josef Mengele (Gregory Peck). The plan is revealed over the course of the film and involves the deaths of 94 middle aged men as well as some science fiction concepts

The character of Ezra Lieberman (Yakov Liebermann in the Ira Levin novel) is thought by many to be modeled on the famous real life Nazi hunter Simon Wiesenthal.

Olivier plays a Nazi hunter in this film whilst in Marathon Man (1976), he played Dr. Christian Szell, an evil Nazi doctor. Szell was known as 'The White Angel', whereas Mengele was known as the 'Angel of Death.'

Olivier's character also bears a resemblance to Dr. Carl Gustav Jung, Swiss psychiatrist.

Both of the lead actors, Gregory Peck and Sir Laurence Olivier, played General Douglas MacArthur in films produced roughly the same time as The Boys From Brazil, Peck in MacArthur (1977) and Olivier in Inchon (1981). Coincidentally, Jerry Goldsmith was the composer for each of those films.

Peck's suprisingly effective performance as the evil Mengele contrasts with the heroic roles he was most famous for playing, notably Atticus Finch in To Kill a Mockingbird.