Though old Matthew the zookeeper has checked all the locks, somehow the animals escape to wander the city, where, to Matthew's astonishment, no one seems surprised to see them mingling with the pedestrians, while a rhino helps itself to a child's ice cream and an elephant plays in a fountain. And no wonder—it's all Matthew's dream. Awaking, he finds the animals safe in their cages; but what is this souvenir in the lion's cage? There's not much plot here, but the details are imaginatively developed—especially in the illustrations, rendered in pastels with luminous white lines highlighting delectable night-muted colors and the cages' geometry as an elegant counterpoint to the action. (Picture book. 4-8)