On top of a high, rocky mountain lives Gnarlytooth, a big, cranky mountain lion. He watches Clicker, the dog, every day and sees how all the animals love him. Oh, how Gnarlytooth wishes he had friends too. What is making Gnarlytooth so cranky? Will Gnarlytooth become a nice mountain lion and make friends? Will Clicker ever become his friend? One day, something amazing and scary happens to Gnarlytooth. Discover how a farmer, a dog and a big, gnarly tooth change a mountain lion's life forever!