Ralph is a talking mouse who lives in the Mountain View Inn in Northern California. He and his mouse family reside in the “knothole,” a hole in the wall of Room 215. Ralph tests his mother’s nerve with his love of dangerous adventures. He becomes passionately interested in the toy motorcycle of a visiting boy, Keith, and convinces the kid to let him ride it at night in the hotel’s hallways. He gets into trouble with the little vehicle, which puts his family in danger, and he must solve the problems he’s created or die trying. Ralph’s actions develop the theme of Adventure and Maturity in a Risky World.

Ralph, as the main protagonist of the story, is a mouse-sized version of kids everywhere who, as they grow up, begin to yearn for more adventures than they’re yet able to navigate. He and Keith bond over their mutual interest in motorcycles and exploring the wider world around them. Ralph must become a more mature mouse to save his family and help Keith recover from an illness. His newfound wisdom teaches him that the best adventures are the ones that help others.