He discovers that there is a ring of saboteurs and enemy agents who are trying to destroy ships carrying supplies to the troops stationed in the islands and sabotage the war effort.
The serial was based on the comic strip by Commander Frank V. Martinek, which was approved by the US Navy.
"[2] The Universal serials for 1941-42 were meant to run: Riders of Death Valley, Sea Raiders, Head Hunters of the Amazon, Gang Busters.
This is possibly due to the greater name recognition of the licensed property over the more generic planned serial.
[3] Source:[4] In 1943, a sequel, Don Winslow of the Coast Guard, was released by Universal.