The Gestapo is investigating the theft of explosives from munitions depot storage and suspect him of the theft based on reports of him being the last person to be seen there. He tells Rosseau that he is being watched by the Gestapo and that they will make a briefcase exchange in the war room. When Rousseau arrives at the war room to make the switch, three Gestapo officers push their way in to the room. They walk in and shout that Fischer is under arrest for suspicion of theft of explosives and being a spy.
After the player does the switch quickly, one of the officer will say there's nothing there, but they will instead arrest him under suspicion. He can later be found tied up in a room overlooking the courtyard with a Wehrmacht Commander interrogating him at gunpoint. After meeting with Crowley, the player can sneak in and release him.
If the player frees Fischer, he will join Rosseau's squad if the player fails to plant the charges without getting spotted. He is seen using an MP-40 submachine gun.