This action adventure is based on Jules Verne's The Light at the Edge of the World. It takes place in 1865 on the chilly tip of Argentina in a lighthouse set up to guide ships around the extremely dangerous and turbulent waters of Cape Horn. The lighthouse keeper (Fernando Rey) and his assistant go out to investigate when a strange sailing ship comes too near to the island the lighthouse is on. Denton (Kirk Douglas), the lighthouse keeper's North American apprentice, is left behind. For their pains, the lighthouse keeper and his assistant are killed, and Kongre (Yul Brynner), the ship's pirate captain, goes to the lighthouse and captures Denton. Kongre shuts down the real lighthouse and sets up a false one so that his pirates can prey on the busy ships that must pass nearby. Denton, set loose by his captors on a nearby island, eventually begins to fight back.