The Serpent's Egg is a 1977 English and German film directed by Ingmar Bergman and starring David Carradine as Abel Rosenberg, which is set in 1920s Berlin. This was Bergman's one and only "Hollywood" film. The title is taken from a line spoken by Brutus in Shakespeare's Julius Caesar:

And therefore think him as a serpent's egg

Which hatch'd, would, as his kind grow mischievous;

And kill him in the shell.

Ingmar Bergman's The Serpent's Egg follows a week in the life of Abel Rosenberg, an out-of-work American circus acrobat living in poverty-stricken Berlin following Germany's defeat in World War I. When his brother commits suicide, Abel seeks refuge in the apartment of an old acquaintance Professor Veregus. Desperate to make ends meet in the war-ravaged city, Abel takes a job in Veregus' clinic, where he discovers the horrific truth behind the work of the strangely beneficent professor and unlocks the chilling mystery that drove his brother to kill himself. Written by Leigh Thomas

In November of 1923, in a Berlin where a pack of cigarettes costs four million marks and people has lost faith in the present and future days, the alcoholic and unemployed American acrobat Abel Rosenberg (David Carradine) loses his brother Max, who has just committed suicide after feeling depressed for a period. Seeing the modifications in the behavior of people, but without clearly understanding the reasons, Abel moves to the room of his former sister-in-law Manuela Rosenberg (Liv Ullmann), who works in a cabaret in the night and in a whorehouse in the morning. Together, they move to a small apartment near to the clinic of their acquaintance, Professor Hans Vergerus (Heinz Bennent), who gives a job opportunity to Abel in his clinic. While working in the place, Abel discloses the evil truth behind the researches of Hans. Written by Claudio Carvalho, Rio de Janeiro, Brazil