After being humiliated by the members of the Theatre Critics Guild at an awards ceremony the Shakespearean actor Edward Kendal Sheridan Lionheart (Vincent Price) is seen committing suicide by diving into the Thames from a great height. In fact he survives and is rescued by a group of vagrants. Two years later, beginning on the Ides of March, Lionheart sets out to exact vengeance against the critics who failed to acclaim his genius, killing them one by one in ways very similar to murder scenes in the season of Shakespeare's plays that he last performed. Before each murder Lionheart recites the critic's damning review of his performance in the role.