In September 1920, Inspector Ian Rutledge has a real baffler on his hands: a sniper has just killed two seemingly unrelated men in the Fen country of East Anglia. One was gunned down as he was about to enter a church for a wedding, and a Parliamentary candidate's head was blown off as he began a stump speech. The initial inquiries yielded little and resulted in the locals calling in the Yard, but apart from a woman who claims she saw a monster just as one was shot, there isnt much for Rutledge to go on.