Castor has always been a stray. He knows no other life than the one he has spent in the back alleys of Lion's Head, prowling with his pack. His days are filled with the unknown: Where to eat? Where to sleep? Who to trust? But Castor's tougher than he looks, and he's always gotten by. Until the day that he's captured by a group of strange men. And taken to a dark laboratory full of terrifying creatures. What Castor doesn't know is that there's a nefarious secret society lurking beneath the busy streets of Lion's Head. Scientists who trap stray and exotic animals and create hybrids by injecting them with a DNA-changing serum. They call these extraordinary new breeds Unnaturals. And they force them to compete against each other in an infamous fighting ring for big prize money. Soon, Castor is transformed from a German shepherd mutt into a powerful beast with huge eagle wings. As he's thrust into the ring, he knows he'll need all his courage to survive. But it will take unexpected allies and something even more than courage for him to save the Unnaturals. . . .