Jim's dog has just died, and his best friend, Danny, has moved out of town, but the day the book opens takes an unusual turn when a flurry of girls run, by chasing a monkey. Turns out the escaped primate belongs to Mrs. Monroe, or, as Jim and his sister Mary Al call her, ""Mrs. Million Dillion,"" the richest woman in town. When Jim and Mary Al catch the wayward capuchin, Mrs. Monroe offers to hire them to tame the monkey, and to tame her granddaughter, J.D. The children get along like fire and ice until the decision to fix up a ramshackle treehouse on Mrs. Monroe's property mellows J.D., and reveals how past events have hardened her. Even with its rural Texas setting, the book harbors anachronistic elements; it's hard to believe Jim's shock when J.D. curses--TV and the Interact have exposed children to much worse. Jim is more of a foil to J.D.'s antics than a full-blown character; he's the audience for her misbehavior. Nevertheless, Nelson (Earthshine, 1994, etc.) ensures that the action never falters, and the rush toward resolution will grip readers.