Tom Brown
'Smilin' Jack' Martin

Marjorie Lord
Janet Thompson

Rose Hobart
Trudy Muller, aka Fraulein von Teufel

Keye Luke
Captain Wing

Edgar Barrier
Tommy Thompson

Cyril Delevanti
Mah Ling / Han Po, his double

Philip Ahn
Wu Tan

Turhan Bey
Kageyama [Chs. 1-5, 12-13]

Sidney Toler
General Kai Ling [Chs. 1-5, 13]

Jay Novello
Kushimi, infiltrator [Chs. 1-3, 12-13]

Rico De Montez
Henchman Hito [Chs 1, 4, 12-13]

Nigel De Brulier
The Lo-San [Chs. 2-3, 12-13]

Edward Keane
Hon. George Hill [Chs. 8-12]

William Forrest
Secretary of Internal Affairs [Chs. 8-12]

Jack Gardner
Captain Yoshido [Chs. 1-3]

Terry Grey
Shuma, pilot [Chs. 1-3]

Stanley Blystone
Capt. Hardigan [Chs. 5-6]

Herbert Heyes
Sir Cedric [Chs. 5-7]

James Craven
Commissioner Robert George Hardy [Chs. 5-7]

Alex Havier
Sanson, phoney waiter [Chs. 6-7]

Paul Bryar
Herr Bauer [Chs. 6-7]

Norma Drury
Frau Bauer [Chs. 6-7]

Grace Cunard
Second German Woman Spy [Chs. 6-7]

David Hoffman
John O. Blenker [Chs. 9-11]

Edward Peil Sr.
Freighter Captain [Chs. 7-8]

Wheeler Oakman
Freighter Mate [Chs. 7-8]

Frederick Giermann
Schlesser, device expert [Chs. 10-11]

Bert Freeman
Shimoto, device operator [Chs. 10-11]

Harry Strang
Honolulu Detective-in-charge [Chs. 10-12]