When the astronauts Burke and Virdon, with their chimp companion Galen, are captured in a fishing village that employs human slave labor, they must prove their worth as fishermen or be sacrificed to the 'gods of the sea,' or what the men call sharks. Escaping from the forced labor camp, the trio become involved in a plot to develop a glider to drop a fragmentation bomb on the gorilla council. [The fifth of five telefilms edited from episodes of the 1974 TV series; this film combines the episodes "Tomorrow's Tide" and "Up Above the World So High"].