Charles Laughton stars as barrister Sir Wilfrid Robarts in Billy Wilder's screen version of Agatha Christie's enormously successful stage adaptation of her original story. Although the ailing attorney has been advised by his doctors to cease and desist from the practice of law, his interest is piqued when solicitor Mayhew (Henry Daniell) asks him to take the case of murderer suspect Leonard Vole (Tyrone Power). After evidence that he stood to gain financially from the victim's death comes to light, the man is indicted. Robarts, nonetheless, agrees to defend Vole, convinced as he is of his innocence. But the case becomes even more of an uphill battle when the defendant's supposedly loving wife Christine (Marlene Dietrich) decides to testify as a witness for the prosecution. Wilder expanded Christie's play, creating the role of Robarts' housekeeper Miss Plimsoll (played by Laughton's actual wife Elsa Lanchester), whose badinage with her employer provides a comic counterpoint to the film's melodrama. Bravura performances by Dietrich and Laughton fuel the entertaining courtroom drama, which also features fine work by Tyrone Power in his last screen appearance.