Bosworth's intriguing but uneven debut novel (after the collection A Burden of Earth) starts off with a bang. Due to her superior reading skills, Rachel E. Finch, an asthmatic seventh grader growing up in late 1960s Teaneck, N.J., has been chosen by S-Man, a blue-haired superhero, "to fly to the aid of troubled writers!" Zipping through time with the cape-wearing ("Holy Mother Planet!") S-Man, the adolescent bookworm helps Shakespeare through writer's block, has amazingly erudite encounters with Oscar Wilde, Chinua Achebe, Madame de Pompadour, Aquaman and others, while also battling evil-doers like stinky Malathion, the impish Mr. Stick, arch villain Laff Riot and the brain-sucking Assemblage. It beats real time, where Rachel's parents' marriage is coming apart, her older and more popular sister, Elaine, drives her crazy and racial tensions play out in a city where Malathion insecticide sprays drive citizens into their homes to avoid contamination. Rachel's adventures with S-Man are the precocious 12-year-old's primary coping mechanism; her other consolation is her friendship with fellow book fiend ("You can't not read everybody") Rachel Fish. Lyrical and amusing at its best, the novel is marred by coy authorial intrusions, and the explosive fantasy-meets-reality conclusion is oddly dissatisfying. But Bosworth can be gloriously inventive, and her fantastical coming-of-age novel should prove a treat for superhero-loving bibliophiles. (July 29)