Mrs. Pargeter doesn't much like diets. She never felt any need to change her own pleasingly ample figure, but she's happy enough to accompany her slimming-obsessed friend Kim Thurrock for a few days' stay at the exclusive Brotherton Hall health spa. There's one condition, however.
Mrs. Pargeter must receive a special "allergy treatment" featuring the choice delicacies of a cordon bleu chef and an excellent wine list. Suitably assured of rich food and drink, she relaxes and looks forward to a luxurious rest.
Until ... she sees two men wheeling away a young girl's body. Never one to let a murder go unsolved, Mrs. Pargeter sets off on a dangerous trail of inquiry through the pretensions and occasional charlatanism of the health-and-fitness game. It's a trail that brings her up against many of her late husband's "business associates" - among them, the lugubrious private eye Truffler Mason, journalist Ellie Fenchurch, Brotherton Hall's manager "Ankle-Deep" Arkwright, surgical specialist "Jack the Knife," and the enigmatic Stan the Stapler.