Inspector Bechoux suspects Barnett, a private detective in whom he believes he recognizes Arsène Lupin, of stealing “King Dagobert's treasure” and hiding it. Barnett goes to the church in a small village where Inspector Bechoux has begun his investigation. The theft was committed in the middle of the night by a one-armed man. So Bechoux arrests a one-armed man in the village, interrogates him and hands him over to Baron de Gravières, the local Châtelain, for safekeeping. But Barnett isn't happy with this hasty arrest.