Big Gray, the monster cat introduced in The Ghost of P.S. 42-which PW called ""an agreeable romp""-is back to harass the sibling mice Molly and Jake in Class Pets: Battle in a Bottle by Frank Asch, illus. by John Kanzler. Eschewing the safety of the classroom, Jake pines for adventure and heads out to the playground. There Big Gray stalks him until he takes refuge in a ketchup bottle. Can he escape?