Dorothy (Maureen O’Sullivan) has come home to her elderly inventor father Clyde Wynant, to tell him of her engagement and marriage to Tommy (Henry Wadsworth), set for just after Christmas. He’s intent on leaving right away due to a new invention that must remain completely secret, refusing to tell anyone where he’s going or for how long. When months pass and no one has seen or heard from Mr. Wynant, Dorothy begins to worry. Then, Julia Wolf, Clyde’s secretary and mistress who recently stole $50,000 worth of bonds from him, turns up dead, clutching a prized watch chain worn by the missing man.
All the motives point to Wynant, but the clues lead elsewhere. His ex-wife Mimi always wanted money from him and was the one to discover the body; lawyer Herbert MacCaulay may have been the last one to see him; nerdy younger brother Gilbert desperately wants to get involved; conniving, jobless Chris Jorgenson (Cesar Romero) would love to get some quick cash for Mimi; Morelli likes to interrogate with guns; bug-eyed Arthur Nunheim wants to pin it on Morelli; bookkeeper Tanner likes to snoop around; and everyone wants to stay between the cops (led by low-voiced, emotionless lieutenant John Guild) and the truth. In walks Nick Charles (William Powell), a retired detective with a fine reputation and a glass of scotch permanently in hand, visiting New York in the wrong place at the right time to take the case. Along with his supportive wife Nora (Myrna Loy) and their beloved dog Asta, Nick decides to get to the bottom of it – especially when the body count begins to rise.