1915: After some days leave, submarine commander Liers and his crew put to sea again. As two of his brothers are already killed in action, Liers` mother hate the idea of him going back to his sub. On patrol they sink a British armoured cruiser, but while returning to their harbor, they are attacked by a sub trap. They are able to sink it, but the trap has alarmed a destroyer, that sinks their sub. The sub lays on the sea bed at 200 feet, and except for the bridge, it is full of water. Ten members of the crew survived, but there are only eight rescue devices. Liers gives the order, that the crew shall use them, but they disobey, either all get out or nobody...