Wanda Nash (Carole Lombard), an actress from Brooklyn, decides to masquerade as "Princess Olga" from Sweden in order to land a film contract with a big Hollywood studio. On board the liner ''Mammoth'' bound for New York, she runs into King Mantell (Fred MacMurray), a concertina-playing band leader with a criminal record in his past. Both are blackmailed by Robert M. Darcy (Porter Hall), and after Darcy is killed, they become two of the prime suspects for the murder, and must find the real killer before the five police detectives traveling on the ship can pin it on them.