Through a particularly ill-fated series of events, couch potato Maeve Kelly, an elementary school teacher, has been forced to sign up for the Other Half, Bath’s springtime half marathon. The training is brutal, but Maeve must disprove her mother, who insists that exercise is a waste of her time, and collect pledges for her aunt’s beloved charity. What she doesn’t know is just how vicious some of the other runners are. Meanwhile, Detective Peter Diamond is tasked with crowd control on the raucous day of the race — and catches sight of a violent criminal he put away a decade ago, who very much seems to be back to his old ways now that he is paroled. Diamond’s hackles are already up when he learns that one of the runners never crossed the finish line and disappeared without a trace. Was Diamond a spectator to murder?