In 1945, Nazi soldiers search a Berlin hotel for doctor Martin Richter, an escapee from a concentration camp. Richter pretends to be a waiter delivering a meal to Nazi actress Lisa Dorn. Lisa is suspicious of his behavior but believes him to be an undercover Gestapo man. Meanwhile, facing military defeat, some highly placed Germans make plans to steal a submarine and escape to South America. Armin Van Dahnwitz, who was part of a conspiracy to kill Hitler, is warned by his friend, Baron Von Stetten, that as the last remaining conspirator, he must take the honorable route of suicide. Instead Van Dahnwitz readies his airplane and asks Lisa to fly that night with him to Sweden. Explaining that her work keeps her in Berlin, Lisa refuses and also turns down his marriage proposal. Learning that a waiter who aided him has been captured, Richter tries to escape. Lisa has discovered his true identity, but Richter offers to help her leave Germany with the help of the resistance if she will help him leave the hotel. When Lisa leaves for the theater, Richter crawls through the window of her room and enters the room of fellow Dachau prisoner, Johannes Koenig, a Nobel prize winning scientist. Koenig's experiences have affected his mind, and when Richter speaks enthusiastically of Germany's approaching defeat, he reveals that the Nazis have offered to set up a laboratory for him in South America. Richter argues that it will merely be a front for the Nazi underground. While they talk, Tilli Weiler, the hotel hostess, and a maid explore Lisa's suite and find a jacket that Richter left behind. Hoping to obtain the reward for Richter's capture, Tilli reports to Commissioner Joachim Helm but receives nothing. She leaves his office and finds Mrs. Bauer, the mother of her Jewish fiancé Max, waiting for her. Mrs. Bauer tells Tilli that Max did not die in the concentration camp, but was liberated by American soldiers. Back in her room, Lisa finds Richter dressed in a Nazi uniform. Eavesdropping at her door, Helm learns that she is planning to leave and enters her room, where he finds Richter. The two men struggle and Richter kills Helm. Learning that he will not be able to escape the S.S., Van Dahnwitz shoots himself. In the meantime, the Nazis have found Helm's body and send a troupe of S.S. to surround the hotel. By pretending that Richter is drunk, Lisa gets him outside the hotel, but when Von Stetten tells her that the Gestapo think she was involved in Helm's murder, she offers to trade Richter and his knowledge of the underground for a safe passage out of Germany. Members of the underground kidnap Lisa and bring her to their headquarters, where Tilli, Mrs. Bauer and a reformed Koenig wait to leave the country. Shocked by Lisa's betrayal, Richter shoots her. As the Nazis prepare to leave the hotel, an Allied bomb squad passes overhead.