
"Mike Shayne battles smugglers and spies to keep them in the U.S.A. It's his most dangerous assignment!"
In order to win back his girlfriend, Mike Shayne promises to give up his detective practice and get a job as riveter in an aircraft plant. He quickly finds himself investigating the theft of industrial diamonds from the plant's safe and, utilizing a variety of false identities, traces them first to a dress factory and later to a Hawaii-bound ocean liner. Escaping several attempts on his life, he is able to uncover a Nazi smuggling ring, but the location of the missing diamonds continues to elude him.
Michael Shayne

Merle Garland

Juan Arturo O'Hara

Helen Shaw

Vanderhoefen

Rudolf Hagerman

Friedrich Gerber, alias Nappy Dubois

Ethel

Charlie

Mrs. Bertha Toby

Mr. Toby

Alexis Fournier

Judge

Capt. Brown

First Officer Richards

Inspector Peterson

Joseph P. McCordy

Miss Hoffman

Theodore H. Sherman Jr.- Printer

Clerk (uncredited)

Man at Ship Dock (uncredited)
Ship's Passenger (uncredited)

Helper (uncredited)

Mrs. Flaherty - Mike's Landlady (uncredited)

Honolulu Cop (uncredited)

First Junior Officer Brooks (uncredited)
Man at Ship Dock (uncredited)

Jonesy

Ship's Purser

Porter

Maid
Taxi Driver
Salesgirl

Taxi Driver
Ship's Doctor

Felix
Ship's Pageboy
Police Sergeant

Thomas

Court Clerk

Kali - Chauffeur
Barney - Cop

Sailor Carson

Ship's Doctor

Truck Driver

Ship's Ticket Agent

Otto
Minor Role