Tracking down runaway teenage girls is a staple of hard-boiled shamus fiction, and that's what Boston's Spenser is up to in this slight, efficient episode--a modest comeback after the tedium of 4 Savage Place. The girl is April Kyle, a suburban high-school dropout who was befriended by guidance-counselor Susan Silverman (Spenser's beloved). So, though he refuses to work for April's foul father, Spenser does go sleuthing, paying his own way. (He seems to be independently wealthy these days.) On, then, to Boston's Combat Zone--where a rough trail of hookers and pimps leads to a Providence brothel: Spenser rescues April; preferring not to be rescued, she runs off again. And Spenser, with Susan and enforcer-pal Hawk, finally zeroes in on the State Education official who's running a teen sex/porn ring from his Back Bay townhouse: after an orgy/brawl, the vice-king is nabbed--but, in a provocative fade-out twist, Spenser sends April not home. . . but to a classy brothel in New York. ("The best we can do is give her a chance to sell her body less often for more money.") No mystery, fewer laughs than usual, lots of one-on-one violence--a predictable yet swiftly readable Spenser, without the pretentious chitchat that has bogged down some of his recent outings.