The Kallinov jewels were, for the first time in many years, to be collected together under one roof, and John Mannering was invited to add his own Gloria diamonds. What was not realised, however, was that Mannering was in fact the legendary 'Baron', a highly successful jewel thief! Then, Mannering hears a gunshot in the middle of the night and witnesses the entire collection being driven away by thieves.To make matters worse, he then receives a note from the thieves which makes it abundantly clear that he is probably going to be framed for the theft, and so finds himself hemmed in from all sides.