Even if Nico-the-Mosquito didn't remind Spencer every day at school that he's a big, fat loser, there's no way Spencer could forget. For starters, there's the big game he blew for the whole team last Saturday. Darn his stupid leg that can't grow muscle! It's hard to make even the easiest tackle on the planet when you run like a three-legged dog. He'll never be a football star like his big brother, Chase. Not in a million years. And since the only kids who matter at school are the athletes, Spencer's more than just a loser - he's a nobody. His skinny leg has seen to that. 

Then Spencer reads Jack London's The Call of the Wild and intrigued by the story of sled dogs during the Yukon gold rush, wonders if mushing is a sport he can do. His parents, eager to boost their son's self-confidence, agree to let him get some dogs. Spencer ends up with dogs that other mushers no longer want - team-rejects just like himself. 

In an extraordinary journey of self-discovery, perseverance, and love, Spencer and his misfit dogs learn to be a team. When they miss a turn in a blizzard during their first 100-mile race through some of the wildest backcountry on Earth, they each must contribute a unique skill to make their way out alive.