Billy Wilder directed this 1957 mystery movie, based on the Agatha Christie short story and play, and presented tonight as another of TCM’s “Essentials.” And with good reason, because this may be the best Christie mystery ever put on film – and without relying upon one of her colorful intrepid investigators. Instead, Witness for the Prosecution is all about the courtroom, and stars Charles Laughton as an ailing but wily veteran barrister defending a man (Tyrone Power in his final role) accused of murder. The man’s wife, played by Marlene Dietrich, provides the basis for an alibi – but, before long, is called as a prosecution witness. Excellent performances all around, and one truly surprising twist after another, make this a courtroom classic – and, yes, an absolute “Essential.”