A
bottle with a manuscript inside it is thrown into the sea. It floats to the coast of
England, where a sailor discovers the bottle and opens it to read the manuscript. Bowen Tyler narrates. During
World War I, Bowen Tyler and Lisa Clayton are passengers on the ship torpedoed by Captain von Schoenvorts. Along with a few surviving British officers, Tyler persuades the other men to take over the surfacing submarine, this being their only chance for survival. After they confront the Germans on the deck, a fight ensues, and they seize the German
U-boat. Tyler takes command, hoping to sail to a British port. Von Schoenvorts has his crew steer toward a safe sea port, but German officer Dietz breaks loose and smashes the sub's radio. Off course and running out of fuel in the
South Atlantic, the U-boat and its crew happen across an uncharted subcontinent called
Caprona, a fantastical land of lush vegetation where
dinosaurs still roam,
co-existing with primitive man. There are also deposits of
crude oil. If the Germans and British work together, the oil can be refined and enable their escape from the island. Tyler and von Schoenvorts agree to work together. Tyler discovers the secret of Caprona: individuals evolve not through
natural selection but by migrating northward across the island. With the submarine working again, a sudden outbreak of volcanic eruptions occurs across the island. Dietz starts a mutiny, shoots Captain von Schoenvorts, and takes command. He abandons Tyler and Clayton in Caprona in an attempt to escape, but the U-boat cannot function in the boiling waters, and the crew is killed as it sinks. Tyler and Clayton are stranded, and being the only survivors of their group, are forced to move northward. Tyler throws the bottle with the manuscript inside it that's seen at the beginning of the film. ==Cast==