Having finally beaten Pompey's armies, Caesar (Louis Calhern) has returned to Rome to the acclaim of it's population. A fourth term as consul and the title of dictator for life suit his ambitions but they cause alarm amongst those who feel this is the first step to absolutism. First amongst those suspicious characters is Cassius (John Gielgud) and together with Brutus (James Mason) and Casca (Edmund O'Brien) conclude that drastic action needs to be taken if they are to prevent him becoming king. They must, however, factor in the powerful Mark Antony (Marlon Brando) - Caesar's right hand man,…