A German submarine patrols the Atlantic Ocean during World War II, manned by a crew that must contend with tense conflicts and long stretches of confined boredom. While war correspondent Werner (Herbert Grönemeyer) observes day-to-day life aboard the U-boat, the grizzled captain (Jürgen Prochnow) struggles to maintain his own motivation as he attempts to keep the ship's morale up in the face of fierce battles, intense storms and dwindling supplies.