"A chemical manufacturer is killed just after asking detective James Wong to help him. So detective Wong decides to investigate this as well as two subsequent murders."
Boris Karloff
as James Lee Wong
Grant Withers
as Police Capt. Sam Street
Maxine Jennings
as Myra Ross
Evelyn Brent
as Olga Petroff / Countess Dubois / Sophie Dome
George Lloyd
as Devlin
Lucien Prival
as Anton Mohl
John St. Polis
as Carl Roemer
William Gould
as Theodore Meisle
Hooper Atchley
as Christian Wilk
John Hamilton
as Simon Dayton
Wilbur Mack
as Russell
Lee Tung Foo
as Tchin
Lynton Brent
as Tommy
Grace Wood
as Mrs. Roemer
Frank Bruno
as Lescardi (uncredited)
Ed Cassidy
as Ambulance Doctor (uncredited)
Wheaton Chambers
as Chemistry Lab Director (uncredited)
Clancy Cooper
as Warehouse Man (uncredited)
George DeNormand
as John (uncredited)
Lester Dorr
as Coroner (uncredited)
Herbert Evans
as Wilk's Butler (uncredited)
Dick Reinhart
as Dock Worker (uncredited)
William Nigh
Director
William T. Lackey
Producer
Houston Branch
Screenplay
Hugh Wiley
Original Story
Scott R. Dunlap
Edward J. Kay
Original Music Composer
Harry Neumann
Director of Photography
Russell F. Schoengarth
Editor
Gordon Bau
Makeup Artist
Charles J. Bigelow
Production Manager
W.B. Eason
Assistant Director
Harry Grundstrum
Props
Karl Zint
Recording Supervision
Abe Meyer
Music Director
E.R. Hickson
Technical Supervisor