In the midst of World War II, the crew of the submarine HMS Sea Tiger finds their long-awaited shore leave suspended when they're given a new mission. Germany's brand-new battleship, the Brandenburg, is crossing open waters on its way to the Baltic Sea, giving commanding officer Lt. Taylor (John Mills) and his crew a chance to destroy it. But when the ship enters the well-fortified Baltic, Taylor must decide whether to chase after their quarry, not knowing if they can make it out alive.
