This is a lovely picture book with charming illustrations. The clever little gorilla takes the zookeeper's keys and lets the animals out of their cages. They follow the zookeeper home and curl up to sleep in his room, and therein follows a funny sequence of "good nights" that leaves the zookeeper's wife wide-eyed in the dark. Everyone is returned to his cage in the zoo... or are they? There are cute details in the pictures, such as each zoo animal having toys (a Babar stuffed animal for the elephant), and a banana-toting mouse.