The Secret of the Skeleton Key

This by-the-numbers launch to Warner's (The Mystery of the Haunted Caves) Code Busters Club series introduces four seventh graders who enjoy communicating via various codes%E2%80%94including American Sign Language, Morse code, and a mathematical cipher%E2%80%94that are incorporated into the novel and translated in its back matter. Code devotees may find this engaging, but the conceit adds little to this mystery, which involves a sudden fire that destroys a neighborhood hermit's house and a bizarre couple claiming to be his relatives, who the club members assume are searching for the man's buried treasure. In the neighbor's burnt-out house, the young sleuths find clues%E2%80%94written in code, of course%E2%80%94that lead them to the hermit's will and help them foil the villains' plans. Characterizations are thin, and the book's humor, often of a mildly scatological variety, misses the mark. Laborious detail, repetition, and stilted dialogue slow the pace, and contemporary references to C.S.I., Hurricane Katrina, and text message lingo aren't enough to keep this series from feeling dated out of the gate. Ages 8%E2%80%9312. (Aug.)