The day Monica Holloway learns that her lovable, brilliant three-year-old son has autism spectrum disorder, she takes him to buy an aquarium. But what Wills really wants is a puppy, and from the moment Cowboy Carol Lawrence, an overeager and affectionate golden retriever, joins the family, Monica watches as her cautious son steps a little farther into the world.

With his new "sister" Cowboy by his side, Wills finds the courage to invite kids over for playdates, conquer his debilitating fear of water, and finally sleep in his own bed with the puppy's paws draped across his small chest. And when Cowboy turns out to need her new family as much as they need her, they discover just how much she has taught them about devotion, loyalty, and never giving up.

Sometimes it's what you don't know to hope for that saves you. For Monica and Wills, salvation came in the form of a puppy with pale blond fur, chocolate brown eyes, a fondness for chewing the crotch out of underpants, and a limitless capacity for love.