Kelly Easton, . . Candlewick, $14.99 (144pp) ISBN 978-0-7636-1580-2

The titular problem at Aaron Betts's family pet store is that the animals are disappearing, but there are more complications afoot in the plotting of this funny but ultimately disappointing book. The affable fifth-grader launches the novel promisingly enough: "I think of people as animals. My mom, for example, is a canary. She flutters around the store, from task to task, and chirps at the customers as they tell her long stories about their cat's new litter box or their turtle shell's fungus." Quick-witted and mature Aaron works hard in the shop—but his stress surfaces in a few compulsions, such as counting the 264 steps to school each day. A surprising and healing friendship develops between the hero and snooty classmate Sharon (at first, he compares her to a haughty Siamese cat: "Meow, I could practically hear her say"). Easton (The Life History of a Star) sprinkles into the narrative moments of delicious sarcasm, insight and verve, and crafts most of her characters impeccably. But the story splinters into numerous subplots and never quite gathers momentum. The failing pet store, the apathetic parents, the mystery of the vanishing pets, Sharon's crush on Aaron and the neighborhood's gentrification and its effects on a homeless lady crowd the novel until there isn't room to fully explore or resolve all of the issues. Consequently, an exposition-heavy, deus ex machina solution to the "mystery" yields an abrupt conclusion, even though Aaron's narration keeps the plot bouncing along. Ages 8-12. (Apr.)