As a favor to his homeless acquaintance Scratchy, Nick Polo agrees to run down a few license plate numbers without knowing why. Big mistake. By the time Polo has identified the three drivers Scratchy was interested in--would-be San Francisco mayor Lester Maurence, Chinatown gang boss Henry Lee, and dirty-dealing ex-cop Al Davis--a car has backed over Scratchy, Polo's already started to get phone threats suggesting what a good idea it would be if he forgot about the case, and (just to make sure he takes the hint) his longtime tenant Mrs. Damonte is nearly killed in a not-so- mysterious fire at his place. The police aren't likely to find the perps anytime this century--the inspector on the hit-and-run is indifferent, the sergeant on the arson inept, and a pair of cops from Internal Affairs interested mainly in harassing Polo--so Polo determines to run down his only lead: a world-class fake Rolex that Scratchy pawned for $650 the day before he died. The search will lead Polo from friendly drinks with his Uncle Dominic, a prudent bookie, to an evening's brisk exercise with his burglar friend Hootsie; but since Kennealy (Vintage Polo, 1993, etc.), as usual, isn't much interested in coming up with murder suspects, the ending won't elevate your pulse rate dangerously. A little of this, a little of that, not too much of anything: a middling entry in this middling series. Watch out for Polo's incessant editorial asides, though; he's in danger of getting as sententious, in his good-humored way, as Andy Rooney.