It's a dark and stormy night at the mansion of elderly Colonel Claythorne, and the pompous murder-mystery author Arthur Whittington is holding court with the Colonel’s family: his eldest daughter, Clarice, who is cold and glamorous; Clarice’s attractive fiancé, Jasper; Claythorne’s youngest daughter, Dotty, who is a big fan of Whittington’s; and Mrs. Shirley Peck, an unassuming but keenly observant visiting widow. When Whittington shares the news that the Colonel has modified his will to cut out one of his daughters—though which daughter won’t be revealed until the Colonel’s death—tempers flare. By the time Mrs. Peck’s son, (junior) Detective Paul Peck arrives at the house, there’s been a murder, and everyone is a suspect.

With backstabbing, love, and Mrs. Peck’s mother-knows-best advice complicating the investigation, it soon becomes clear that nothing—and no one—is what it seems.