Given DeClements's previous, engaging novels for middle-graders ( Nothing's Fair in Fifth Grade ; Sixth Grade Can Really Kill You ), her latest is somewhat of a letdown. It focuses on Caitlin, a good-natured sixth-grader who shoulders a good deal of responsibility for her age. Because her mother is always exhausted, Caitlin cares for her infant brother in the wee hours of the morning. She also keeps a maternal eye on her good friend and neighbor Bones, so nicknamed because his obsessively frugal mother spends so little money on food. Bones and Missy, who moves into the neighborhood, figure prominently in the mystery that is at the center of DeClements's story. As always, the author's young characters are exceedingly real, yet the plot's pace is disappointingly sluggish. Though readers are kept guessing, the novel does not deliver the suspense suggested by its title. Ages 8-12. (Sept.) (c) Copyright PWxyz, LLC. All rights reserved