Father Brown convinces his friend, Lady Warren, to auction an important gold chess set to lure Flambeau into stealing it. They expect him to appear in disguise at the auction. He does, but not as a bidder: Flambeau is the porter who carries the set out of the room after bidding concludes. But Flambeau returns the set to Lady Warren to prove a point. When the police arrive at the door Flambeau and Brown remove all the milk from the back of a milk van to make it look as if they needed the space. This diversion makes the police follow the van and Brown and Flambeau escape.