A movie serial in 12 Chapters: US naval officer Don Winslow is given command of Tangita Island, near Pearl Harbor, where a ring of saboteurs is trying to destroy ships carrying supplies to the troops stationed in the islands and sabotage the war effort under orders from an unknown leader.

Reparto

Don Terry

Cmdr. Don Winslow

Claire Dodd

Mercedes Colby

John Litel

Spencer Merlin

Walter Sande

Lt. Red Pennington

Anne Nagel

Misty Gaye

Wade Boteler

Mike Splendor

Ben Taggart

John Blake

John Holland

Paul Barsac

Lane Chandler

Henchman Corley

Ethan Laidlaw

Henchman Spike

Peter Leeds

Seaman Chapman

Robert Barron

Henchman Prindle

Kurt Katch

The Scorpion

Ray Teal

Gang Radioman Barker

Dirk Thane

Lt. Cdr. Grady

Herbert Rawlinson

Admiral Warburton [Ch. 1]

Samuel S. Hinds

The CINCUS [Ch. 1]

Kenneth Harlan

Capt. Holding [Ch. 1]

Arthur Loft

Enemy Sub Capt. Tranker [Ch. 1]

Paul Scott

Capt. Fairfield, of the "Batavia" [Chs. 1-2]

Jerry Mandy

Tangita Jim [Chs. 2, 10]

Heenan Elliott

Capt. Sanders, of the "Tarleton" [Chs. 3-4]

Paul Bryar

Saboteur Kramer [Chs. 3-4]

Edward Hearn

Lead Henchman at Mill [Ch. 5]

Iron Eyes Cody

Native Henchman at Mill [Ch. 5]

Frank Lackteen

Witch Doctor Koloka [Chs. 6-7]

Guy Kingsford

Sub Capt. Jackson [Chs. 7, 9]

Ken Terrell

Sam Munn, henchman [Ch. 8]

Jack Rockwell

Henchman Butch [Ch. 8]

Irving Mitchell

Gang Chemist Taylor [Chs. 8-9]

Eddie Polo

Taylor's Lab Assistant [Ch. 8]