A spin-off from the hugely popular television series Skippy, the movie version retains the same central characters: Matt Hammond, Chief Ranger of Waratah National Park; his two sons Mark and Sonny; Jerry King, the young Flight Ranger; and Clancy Merrick, the teenage daughter of another ranger, who works part time at Ranger Headquarters.
The narrative sees Skippy discover a ruthless gang of criminals, led by Meredith, who are searching for lost treasure on the ocean floor. Sonny and Clancy try to investigate but are kidnapped. Skippy manages to bring help, and, after a speedboat chase and a gun fight, the villains are rounded up and brought to justice.