Now and then - Robert B. Parker

Spenser knows something's amiss the moment Dennis Doherty walks into his office. The guy's agressive but wary, but when Doherty asks him to investigate his wife's abnormal behaviour Spenser agrees. A job's a job. Not surprisingly, Spenser catches Jordan with another man, informs Doherty and considers the case closed. But a couple of days later three people are dead. This isn't just a marital affair gone bad. Spenser is in the middle of a hornet's nest of trouble, and he's got to get out of it without getting stung...