Synopsis: A murderer is hiding aboard the S.S. Mammoth, an ocean liner on its way to New York. But he's not the only passenger who is not what they appear -- for example, Princess Olga of Sweden is not royalty, but a Brooklyn actress named Wanda Nash pretending to be a princess to pursue an acting career. She charms concertina player King Mantell, who is actually an ex-con. Things get more complicated when a blackmailer starts extorting the passengers.