Two nuns are attacked on their way back to their priory in Maldon. Fortunately the commissioners arrive on the scene in time for Ralph and Gervase to fight off the attackers. But how is the attack related to the irregularities detected by the first Domesday Book commission and the murder of a local magnate's son?
For the side mystery, my guess was that Humphrey was a pawnbroker but the author's explanation was more fun.