This story begins on an ocean liner docking in New York. As a small package is put into Chan's luggage for safe keeping, the package turns out to be vital evidence that could sink mobster Buzz Moran. At a police banquet in honour of Charlie Chan, Inspector Nelson Gets word that there has been a murder at the Hotentot Club and that Lee Chan has been arrested. Excusing himself, Chan hurries to the club. Chan takes on the case and finds himself in an underworld inhabited by gangsters, blackmailers and murderers. As Chan says "Triangle very ancient motive for murder".