Chester Morris as Horatio 'Boston Blackie' Black

June Vincent as Doris Howell

Richard Lane as Insp. William R. Farraday

Patricia Barry as Joan Howell (as Patricia White)

George E. Stone as The Runt

Frank Sully as Sgt. Matthews

Edward Norris as Igor Borio

Fay Baker as Margie O'Reilly, alias Sandra Doray

William Forrest as Mason Carter

Sarah Selby as Claire Carter

Mary Currier as Helen Kenyon

Bess Flowers as Party guest