Cinnamon Bay Plantation was the ideal Caribbean island getaway―or so it seemed. But for distinguished Harvard economist Henry Spearman it offered diversion of a decidedly different sort and one he'd hardly murder. While the island police force is mired in an investigation that leads everywhere and nowhere, the diminutive, balding Spearman, who likes nothing better than to train his curiosity on human behavior, conducts an investigation of his own, one governed by rather different laws―those of economics. Theorizing and hypothesizing, Spearman sets himself on the killer’s trail as it twists from the postcard-perfect beaches and manicured lawns of a resort to the bustling old port of Charlotte Amalie to densely forested hiking trails with perilous drops to a barren offshore cay.

At Harvard, tenure decisions are a matter of life—or death. For Dennis Gossen, the economics department whiz kid currently being considered for tenure, it's definitely death. When he's turned down by the high-and-mighty Promotion and Tenure Committee, Gossen commits suicide. A Question of Cost Accounting... Or does he? It's hard to imagine why a young man with a brilliant scholarly future—at Harvard or not—would come up with an equation in which the opportunity cost of killing himself (a high price, considering his potential earnings) would be outweighed by the emotional cost of failing to receive tenure. ... Or Utility? Then two members of the P and T Committee are murdered, and it becomes clear to Professor Henry Spearman of the Economics Department that the killer must be on the committee. But which of his illustrious colleagues would have significantly increased his—or her—utility (i.e., happiness) by murdering a faculty member or two? Or three?

Harvard professor Henry Spearman―an ingenious amateur sleuth who uses economics to size up every situation―is sent by an American entrepreneur to Cambridge, England. Spearman's mission is to scout out for purchase the most famous house in economic Balliol Croft, the former dwelling place of Professor Alfred Marshall, John Maynard Keynes’s teacher and the font of modern economic theory. A near miss for the American entrepreneur and the shocking and bizarre murder of Nigel Hart, the master of Bishop’s College, soon make it clear that the whole affair is risky business. When a second corpse turns up, Spearman is jolted into realizing that his own life is in peril as he finds himself face to face with the most diabolical killer in his experience.