Charlie Chan (Roland Winters) is a private investigator living in San Francisco. One day a Chinese princess comes to visit him in his home. She has just arrived from the East by boat. The princess manages to give Chan’s butler Birmingham Brown (Mantan Moreland) an artifact - an ancient heirloom ring - before she is shot and killed by a poisoned arrow through the window. She leaves a note behind, with the name ”Captain K”. Chan calls for the police to investigate this murder. Bill Davidson (Warren Douglas) with the SFPD comes to Chan, but his friend, the reporter Peggy Cartwright (Louise Currie), also arrives uninvited to the scene.