A brown bear cub named Thor fights to survive on the wild coast of the Alaskan Peninsula – home to a dangerous grizzly empire. Staying alive is his biggest challenge in this unforgiving kingdom, where status must be fought for and won. In his first summer, battles put Thor and his family’s lives in jeopardy. The murderous result of one battle is so shocking and has rarely been witnessed even by brown bear experts. This brutal event has likely never before been seen on television. National Geographic investigates the stakes that these grizzlies face in defending themselves in an empire where life is harsh for even the strongest kings among them. Can Thor and his siblings make it through the most dangerous year of their lives?