One misty November morning, a woman's body is found near a reservoir by three boys collecting firewood for Guy Fawkes night She turns out to be the wife of Monk Ritchie, an escaped criminal - and she has been murdered Detective Sergeant Patrick Petrella has a personal interest in the case, for his colleague still lies unconscious after a beating by one of Ritchie's gang Petrella's enthusiasm leads him to working overtime, by night, in the reservoir