Mantan Moreland provides comic relief as Chan's assistant and chauffeur, Birmingham Brown.

Charlie Chan (Roland Winters) and Number One Son, Lee (Keye Luke), are passengers aboard a commercial airliner headed for San Francisco.

Minutes after drinking coffee that was served, everyone on board the plane falls asleep, including the crew.

A closer look reveals that one of the couriers has been stabbed to death and that the insurance money he was carrying is missing.

After the plane safely arrives, Chan and son, along with assistant, Birmingham Brown (Mantan Moreland), take on the case.