Jack Holt
Jack Holt / Nick Farrell
Evelyn Brent
Kay Drew
John Ward
'Lucky' Arnold
Ted Adams
Quist
Joe McGuinn
'Crimp' Evans [Chs. 1, 4-15]
Tris Coffin
Ed Valdin [Chs. 1-10]
Stanley Blystone
Garrity [Chs. 11-15]
George Chesebro
Rankin [Chs. 11-15]
Stanley Price
Dent [Chs. 11-15]
C. Montague Shaw
Chief John W. Malloy (as Montague Shaw)
Edward Hearn
Agent Jim Layton
Jack Cheatham
Agent Frank [Chs. 3-5, 8-9, 15]
Ray Parsons
John Severn - Engraver [Chs. 1-4]