In this rambunctious comedy, David Wilson (Tony Curtis) is an assistant professor caught by his wife, Ann (Janet Leigh), in a misunderstanding when a grateful student kisses David as Ann walks into the room. Ann is about to leave David, so David asks his friend, Michael (Dean Martin), to help him get her back. Michael comes up with a story that David is an FBI agent and that the girl is a Russian spy. However, their con reaches the point where an actual FBI agent (James Whitmore) starts following them, leading to a series of adventures where the lies get bigger and the laughs get larger.