Unstoppable is exciting and sad at the same time. Harrison never played a football game before, and now he's unstoppable. His coach is also his new foster father and he's very impressed with Harrison. Then Harrison loses the lower half of his leg to cancer. He gets a new lower leg and trains with it every day. He also starts lifting weights.
At the end of the story he manages, with his new lower leg, to get onto the kickoff team. The story was amazing!