After Marco and Polo, two pampered house cats, escape one day into the world outdoors, they find themselves undertaking three dangerous missions in order to earn their membership in a cat gang known as the Club of Mysteries. Suspense and humor will hold the attention of young readers.

They've always been indoor cats, but a taste of freedom sets Marco (indolent but smart—he can read) to scheming; he and Polo (livelier, with a penchant for eating stringy things like spaghetti and ribbon) sneak out of the Neals' comfortable house to make new friends and perform, with spunk and ingenuity, the initiation tasks imposed by the tom who presides over the garbage back of the fast-food place. Naylor, an amused observer of her own cats, characterizes these two with insight and wit, endowing them with believably catlike thoughts, comical misconceptions based on their limited experience, and appealing individuality. Aside from the quests, their behavior is entertainingly realistic—including a retreat home when the food supply is closed out; and though there are now two feisty territorial kittens there, the Neals welcome their old pets back with the recognition that they'll be ``indoor-outdoor'' cats henceforth. An unusually engaging animal adventure, with plenty of sharply observed, action-filled illustrations. (Fiction. 8-12)"