Tonk isn't your average American squirrel. While most squirrels are content living in their home tree for the entirety of their lives, little Tonk is curious. He wonders what's out there beyond the End of Things. What lingers over the horizon? What has he never seen? One day, he hears of a magical flying squirrel held captive in a place called "The San Diego Zoo," and Tonk knows his time has come. He will rescue the squirrel and learn to fly.
He leaves his family behind and sets forth on a dangerous journey to rescue the legendary squirrel with the hope that he, too, can learn how to fl y. But Tonk doesn't know how to survive out there alone. He makes friends with Bogey, a crusty old jackrabbit; El Curador, a Mexican museum mouse; and Pockets, an alarmingly awkward pelican. His friends show him the way to the mysterious zoo.
In the process of saving the young flying squirrel, they must face the enemies that protect her; in so doing, Tonk becomes much more than a young squirrel-he becomes a hero, with his brave buddies to back him up. In the end, he might do much more than save a damsel in distress; he might fall in love. Who says you have to be big to make a difference?