The day after John Francis Cuddy stops to help a birthmarked kid named Eddie Haldon and his uneasy companion, Melinda, change a flat tire en route from New Hampshire to Boston, a floater off South Boston shows every sign of being Melinda, with no sign of Eddie at all. The South Boston police don't want to muddy the waters, and the police in the Haldons' hometown of Elton, N.H., are less interested in Cuddy's story of the man who was pursuing Eddie and Melinda than in covering the Eltonian hide. Cuddy, who promised Eddie he'd come looking for him if he disappeared, ignores the Haldons' claim that they'd sent Eddie away to a religious school and breaks into the shack of the pursuer, Lonnie Severn -- triggering a chain of events that will leave Severn dead and Cuddy trolling the Florida Keys around the Church of the Lord Vigilant. There's not much to do on Little Mercy Key, where Rev. Royel Wyeth's secluded Center for the Study of Sin is located, and Cuddy, bankrolled by a fistful of Severn's money, is in no hurry, so this part of the story drags while Cuddy, ever the Boy Scout, fights off the barmaids and hookers who come on to him while he's meeting the people who'll help him bring down Wyeth and his treacherous wife. Cuddy's done fine work before (Act of God, 1994, etc.), but this sluggish pastiche of Travis McGee, with its unseemly debts to A Tan and Sandy Silence and The Green Ripper, shows him at his most tiresomely virtuous. You may abhor the bad guys, but you just want to pinch the avenger.