Bad Business (2004)

In his 31st outing, Boston PI Spenser muses, ''I always hoped that I'd have a case where one day I could use the phrase 'cause a stir on wall street.''' And so he does: hired to trail a philandering husband, Spenser stumbles across financial chicanery, a couple of murders, and rampant wife-swapping in corporate America. While the dominoes tumble fairly predictably, Parker keeps the dialogue snappy, Spenser's sexy banter with his psychiatrist girlfriend adding spice to an already kinky whodunit.