Late one night, Charlie Chan is shot at a San Francisco bus station. While on a missing-persons case, he investigates a series of slayings terrorizing the city. He is assisted officially by detective Jeff Hay and police captain Allen, and unofficially by his Number Two Son Jimmy and chauffeur Birmingham Brown.
Sidney Toler had been diagnosed with terminal cancer, but insisted on continuing his commitment to the film series. The studio accommodated him by granting him prolonged breaks for rest, and staging the scenes so as not to tax his strength. The studio conserved Toler's energy and spared him from extended movement; Toler is seated during much of the film. Although Toler remains the central actor, some of the action is diverted to Jimmy (Victor Sen Yung) and Birmingham (Mantan Moreland). To lengthen the running time of the film, a two-minute prologue was added, detailing the workings of a bureau of missing persons. None of the film's featured players appeared in this sequence.
