Kirk Alyn

Inspector David Worth

Rosemary La Planche

Laura Keith

Roy Barcroft

Spade Gordon

Carol Forman

Nila

James Dale

Agent Steve Evans

Bruce Edwards

Prof. Paul Williams [Chs. 1-6]

James Craven

Prof. James Clayton [Chs. 1, 10-12]

Dave Anderson

Porter [Ch. 9]