Cap Stone was an adventurer who accidentally became a member of a vast undersea kingdom known as the city of Aquari. He batteld the villainous Triton. Stone believed his nemesis had perished after his aero-car hurtled off a cliff, but Triton crawled from the wreckage alive. Trtiton then sought new allies to conquer Aquari which he found in the banished King Zero of Aquari and his Coral Men. The villains kidnapped Stone’s girlfriend Dohra, but Stone freed her and then captured both Zero and Triton.