The film is loosely based on the 1942 assassination of Heydrich, the Nazi Reich Protector of German-occupied Bohemia and Moravia during World War II.

In Prague, during the Nazi occupation of Czechoslovakia, surgeon Dr. František Svoboda, a member of the Czech resistance, assassinates the brutal "Hangman of Europe", Reichsprotektor Reinhard Heydrich.

Because the assassin now cannot be found, the Nazi leaders take hostages and threaten to execute them, all 400, forty at a time, until the killer turns himself in or is betrayed by his own people; it doesn't matter if they are sympathetic to the Reich, fearful for the life of loved ones slated to die, or imagine doing so will limit the bloodshed, the result will be the same.

[3] Teresa Wright, John Beal and Ray Middleton were also considered at one point to appear in the film,[2] which went into production in late October 1942 and wrapped in mid-December of that year.

It is claimed that the money he earned from the project enabled him to write The Visions of Simone Machard, Schweik in the Second World War and an adaptation of Webster's The Duchess of Malfi.

John Wexley received sole credit for writing the screenplay after giving evidence to the Writers Guild that Brecht and Lang had only worked on the story.

Hangmen Also Die had a world premiere in Prague, Oklahoma on 27 March,[6] an event which featured Adolf Hitler, Hirohito and Mussolini being hanged in effigy on Main Street.

Eisler only worked on a small number of American films, the most notable of which are Deadline at Dawn (1946) and None But the Lonely Heart (1944), for which he was also nominated for an Academy Award.