Mr. Moto's Gamble

In this mystery programmer, a prizefighter dies in the midst of a match, but evidence suggests that it was a dose of poison that killed him rather than the violence of the bout. Mr. Moto (Peter Lorre), a detective who also teaches sleuthing to others, is called in to find out who killed the boxer and why. This movie began as "Charlie Chan at the Ringside," but after Warner Oland became seriously ill during filming, it was rewritten for the screen's other well-known Asian detective in order to make use of the footage that had already been shot.