Blackie is the natural suspect when an expensive pearl necklace is stolen while he is supposed to be guarding it.
| Actor | Role |
|---|---|
 Chester MorrisHoratio 'Boston Blackie' Black | Horatio 'Boston Blackie' Black |
 June VincentDoris Howell | Doris Howell |
 Richard LaneInsp. William R. Farraday | Insp. William R. Farraday |
 Patricia BarryJoan Howell (as Patricia White) | Joan Howell (as Patricia White) |
 George E. StoneThe Runt | The Runt |
 Frank SullySgt. Matthews | Sgt. Matthews |
 Edward NorrisIgor Borio | Igor Borio |
 Fay BakerMargie O'Reilly, alias Sandra Doray | Margie O'Reilly, alias Sandra Doray |
 William ForrestMason Carter | Mason Carter |
 Sarah SelbyClaire Carter | Claire Carter |
 Mary CurrierHelen Kenyon | Helen Kenyon |
 Bess FlowersParty guest | Party guest |