Beverly Cleary has written all kinds of books (the most successful ones about the irrepressible Henry Huggins) but this is her first fantasy.
Actually it's plain clothes fantasy grounded in the everyday—except for the original conceit of a mouse who can talk and ride a motorcycle. A toy motorcycle, which belongs to Keith, a youngster, who comes to the hotel where Ralph lives with his family; Ralph and Keith become friends, Keith gives him a peanut butter sandwich, but finally Ralph loses the motorcycle—it goes out with the dirty linen. Both feel dreadfully; it was their favorite toy; but after Keith gets sick, and Ralph manages to find an aspirin for him in a nearby room, and the motorcycle is returned, it is left with Ralph....
The whimsy is slight—the story is not—and both its interest and its vocabulary are for the youngest members of this age group.
(Fantasy. 8-12)