A joyous demolition party in a holiday camp for teenagers which is inaugurating, just next to its old premises, new brand new buildings. To celebrate, a few elders were invited before the opening by one of their comrades, who had become the camp director. But the party turns tragic. After just a few sledgehammers, we discover a skeleton, immured in an old chimney! So who is he? We will call it "Garenne", like the holiday camp where we found it, Château-Garenne.