Half CIA/politics suspense, half YA-ish adventure: an implausible but solidly entertaining thriller from the author (a.k.a. Tom Lewis) of last year's effectively grim Rooftops. Joe Ball, a veteran CIA man in Southeast Asia, has been forced into early retirement in the late '70s; so, though angry, he has settled down in Washington--caring for 16-year-old son Billy, living (somewhat guiltily) off a fortune in secret accumulated loot, running a storefront income-tax agency as a tax dodge. Then, however, Joe is sucked into a rightwing, Watergate-style scheme involving the Democratic National Committee--a double-twist scheme in which he, all unbeknownst, is to be a corpse and a fall guy. Thus, an assassin is soon going after Joe; Joe manages to kill him, dumping the body into Chesapeake Bay. . . with help from Billy, who must now be filled in on his father's quite shady past. And when Joe is then kidnapped in N.Y., young Billy becomes the central focus of the novel--as he shoots intruders with a silencered .22, finds his father's hidden loot, takes off for Manhattan, shacks up with teenage runaway Annie (a weight-lifter), and eventually falls in with some street-smart black kids (messenger-service employees). . . who become ""Billy's army"" when he must rescue his father from the bad guys. True, neither the lunatic D.C. conspiracy nor Billy's violent coming-of-age is really credible here; and the kiddie-cuteness doesn't always mesh well with the well-evoked dirty tricks. (For a far subtler variation on the Treasure Island kid-against-vice formula, see Norman Lewis' Cuban Passage, p. 363.) But Babcock moves things along briskly, with sweet touches in the kooky-romance department--so readers partial to a violence/sentiment blend (YA or otherwise) will find this a lively and gritty diversion, despite its many contrived moments.