During World War I, a German U-boat sinks a British ship and takes the survivors on board. After it takes a wrong turn, the submarine takes them to the unknown land of Caprona, where they find dinosaurs and neanderthals.

After a German U-Boat sinks their ship, several survivors manage to take control of the boat. Bowen Tyler is the son of an American shipbuilder and Captain Bradley an experienced seaman. After several tussles with the German crew, they find themselves on a strange island. There they find a place where several stages of Earth's evolution co-exist at the same time. As a result several types of humans are found as well as prehistoric dinosaurs. There are also active volcanoes which all add up to a challenge to survive.—garykmcd