He takes an old shotgun he used as a child while hunting with his father and sabotages the chateau's bridge before he starts to kill them one by one, taking advantage of his knowledge of the secret passages within the chateau.
He takes an old shotgun he used as a child while hunting with his father and starts to kill them one by one. They begin to think they are surrounded by many partisans and do not realise that he is, in fact, the only one, taking advantage of his knowledge of the secret passages within the chateau.