An adaptation of Lothar-Günther Buchheim's 1973 German novel of the same name based on his experiences aboard , the film is set during World War II and follows U-96 and its crew, as they set out on a hazardous patrol in the Battle of the Atlantic. It depicts both the excitement of battle and the tedium of the fruitless hunt, and shows the men serving aboard U-boats as ordinary individuals with a desire to do their best for their comrades and their country.