The movie was based on the 1988 book of the same name by Nicholas von Hoffman;[1] it was filmed on location in Pittsburgh, Pennsylvania.

The film spans Cohn's life from childhood through his initial rise to power as McCarthy's right-hand man in the Senate Permanent Subcommittee on Investigations hearings and his eventual public discrediting a month before his death in 1986 from AIDS.

It is told mostly in flashback as Cohn lies dying at a hospital in Bethesda, Maryland, hallucinating that his many enemies (from Robert F. Kennedy to Ethel Rosenberg, a convicted Communist spy he sent to the electric chair) are haunting him.

It concerns aspects of Cohn's life such as his closeted homosexuality and the measure of his culpability in the "Red Scare" of the 1950s.

While the movie portrays Cohn in a decidedly unsympathetic light, it also depicts episodes in his life, such as the death of his beloved mother, in which he showed a more humane, compassionate side.