The Unsuspected

The Unsuspected is a 1947 American blackandwhite film noir directed by Michael Curtiz, and starring Claude Rains, Audrey Totter, Ted North, Constance Bennett, and Joan Caulfield. The film was based on the novel written by Charlotte Armstrong. The screenplay was cowritten by Bess Meredyth, who was married to director Curtiz.

Victor has also recently lost a niece, Matilda Frazier, presumed dead from a boating accident. But at a birthday party thrown by another niece, Althea, everyone is surprised by the appearance of Steven Howard, who claims to be married to the missing Matilda.Victor is accompanied by his radio producer, Jane Moynihan, at the party. He is unsure what to make of the stranger, particularly with a family estate to be settled, and asks a detective named Donovan to investigate. Matilda turns up, but claims to have no memory of Steven or their marriage, despite his efforts to prove it to be true. Acting suspiciously, meanwhile, is Altheas husband Oliver, drinking heavily. ........

Source: Wikipedia