Travis McGee's 20th--which finds him enjoying life on his Florida houseboat, trying to keep his affair with hotel-manager Anne Renzetti on an even keel. But then best friend Meyer's niece Norma dies violently--when she and her charming new husband Evan go for a honeymoon trip on Meyer's cruiser. . . which blows to smithereens. The question for McGee and Meyer: was Evan on board when the explosion hit? There's enough evidence to the contrary to send them on the trail into Evan's past--which involves pseudonyms, stripped bank accounts, unsolved disappearances, and a string of "accidental" deaths. Eventually, then, the sleuths wind up in upstate N.Y. with Evan's sister Helen June, a slatternly trailer-dweller surrounded by rust and junk. And her confessions lead McGee to Mexico, gorgeous Barbara Castillo (an indirect victim of the murderer), and a plan to trap the culprit. Surprises? Very few. But if MacDonald's formula varies little, the shrewd vignettes of places and people continue to be vividly engaging--and his masterly pacing ensures absorbing, taut reading every time around.