During World War I, a German U-boat torpedoes a British merchant ship. A handful of survivors, including American Bowen Tyler and biologist Lisa Clayton, manage to board the submarine in a desperate bid for survival. While the British and Germans clash within the submerged vessel, they eventually find themselves united against the dangers of the unknown as they get lost at sea. Through a series of navigational errors, the U-boat drifts into uncharted waters and comes upon a mysterious, fog-enshrouded island in the South Atlantic.

Upon exploring the island, they discover a prehistorically preserved world where time seems to have stood still. Dinosaurs and primitive tribes co-exist in this hostile environment, creating numerous life-threatening challenges. As resources dwindle and tensions rise between the stranded groups, they struggle to repair the damaged submarine and escape. Their survival hinges on cooperation and adaptability amidst an increasingly perilous landscape filled with ancient creatures and environmental hazards.