After Eric Glenn's dog, Buster, apparently drowns in the river, the animal's searching soul is switched with that of a giant prehistoric saber-wolf, Lopoz. The killer thunder wolf returns to the land of southern Wisconsin that he once terrorized during the last Ice Age, 10,000 years earlier. With worlds out of flux, Eric, friends, and family are cast into a fantastic journey of hope and fear, awaiting the ultimate deliverance and final peace of the fabled THUNDERBIRD, in the page-turning climax