 A Swedish princess boards an ocean liner in Europe en route to an acting career in America, and finds herself getting inconveniently attached to a bandleader returning home. To complicate matters, a blackmailer on board apparently knows she is not who she claims to be - and he has his sights set on other passengers with secrets of their own. In the meantime an escaped killer has stowed away under someone else s identity, and is killing again to cover his tracks; five international police detectives on board are heading the investigation to find him. When evidence points to the princess and bandleader, they must find the killer themselves - before he finds them.