In 1981, a film about the misadventures of a German U-boat crew in 1941 becomes a worldwide hit almost four decades after the end of the World War II. Millions of viewers worldwide make Das Boot the most internationally successful German film of all time. But due to disputes over the script, accidents on the set, and voices accusing the makers of glorifying the war, the project was many times on the verge of being cancelled.

Jonas is in his mid-twenties, still lives with his parents and gets dumped by his girlfriend. He soon gets to know Lena, a tough young woman with ideals, and immediately falls in love with her. However, to prove he is worthy of her love, he has to pass an endurance test.