Spring 1945: the Allies are outside Hamburg. In front of a movie theater, Lena Brücker meets Hermann Bremer, a marine assigned to the 'final battle on the home front'. After a night of love, Lena offers to hide the young man in her apartment during the last days of the war. This marks the beginning of a life-threatening love adventure for both of them, which they must keep secret from the rest of the world. While Lena blossoms over the next few weeks, Hermann suffers from his confinement and the constant fear of being discovered. Nevertheless, Lena will not tell her lover that the war is over so that she can spend as many days as possible with him on their shared 'mattress island' while everything changes outside.