Fair Oaks High School student Brandon Henshaw, a 14-year-old incorrigible, fluent in Spanish, pig Latin, and video-arcade lingo, skips detention (again); and when young widow Carrie Pritchard, the attendance monitor, tracks him down, his excuse is (typically) a whopper: his friend Felipe has been kidnapped, and he had to cut school to find him. Carrie is skeptical, Brandon is remanded to Juvenile Hall, then escapes, and--to his and Carrie's horror--soon trips over a body at the far end of the MacGraws' orchard. Also there, dripping blood: Felipe's knife. Soon this odd-couple detecting team are wending their separate ways to Mujueres in the Yucatan, where Brandon recognizes certain accents as Honduran, not Mexican; Carrie purchases a charming facsimile of a Mayan treasure; Felip is seen alive, then found dead; and Carrie is having troubling second thoughts about all these quick-death thrusts to the heart--that's how her husband, a clinic doctor, was killed, too. . . Meanwhile, there's another murder (Mr. MacGraw); Carrie discovers old X-rays hinting at extensive plastic surgery for someone; and Don Marquez, the school principal, is acting kind of peculiar--for an educator, that is, not for ""one of Somoza's right-hand men before the Revolution in Nicaragua."" A final plane crash eliminates the bad guys, ends an art-smuggling scheme, and resolves all the murders--including that of Carrie's husband. The Carrie/Brandon relationship is warm, rich, and quite charming; but not so the plot, which twists awry in several sequences. Best passage: the night in the hammock on Mujueres. For a first novel, give it a C.