The day after the death of his beloved sister Drusilla, with whom he had a morbid relationship,  Roman Empearor Caligula wakes as a new man. 
He suddenly discovers that the world he lives in no longer is satisfactory. His mad search for freedom goes through murder, perversion of any values, cruelty, abuse. He's an artist and an animal, led by a frenetic passion for the impossible, or, maybe, as Camus himself states, a superior suicide.