Gestapo officer von Hapen has just realized he's been played for a fool by the seductive barmaid Mary. She and her cousin Heidi got him to take them up to the Schloss Adler for a one night stand (or so it would seem). But suddenly Heidi is gone and Mary can't seem to properly remember small details about her supposed hometown of Dusseldorf.
Suspicious, von Hapen escorts her to her room, then heads off to discuss the matter with General Rosemeyer and Colonel Kramer, who are interrogating an American general in the dining room. Upon entering, von Hapen is surprised to find five men he doesn't know present, and a guard lying dead on the floor. One of the men has an MP40, the other a suppressed Walther PPK.
Von Hapen draws his Luger and holds everyone at gunpoint, forcing both men to drop their guns, demanding to know what is going on. One of the men, the one who'd been holding the PPK, introducing himself as Johann Schmidt, tells von Hapen he has uncovered a plot to assassinate Hitler, which hardcore Nazi von Hapen immediately buys.
Schmidt explains he has the names of all the conspirators in a notebook in his pocket, which von Hapen demands to have. Schmidt obliges, but hesitates curiously as he walks in front of the man who'd been holding the MP40. This man yells out "Smith!" and Schmidt - in reality John Smith - dives out of the way as American officer Morris Schaffer, having pulled a Walther of his own while Smith was blocking von Hapen's view of him, fires before von Hapen can react.
He shoots the Gestapo officer twice, in the chest and then in the forehead, killing him instantly.