In Honolulu, Charlie Chans home, a Scotland Yard detective is murdered in Chans office as he is about to reveal the identity of an international killer. When clues point to the murderer being one of the passengers on a ship bound for San Francisco, Charlie Chan decides to join the cruise with his Number Two Son Jimmy. More murders and intrigue take place before Chan is able to announce the identity of the killer with the help of the supposedly blind widow of the first victim.