Boog the grizzly bear is a lucky fellow, utterly pampered by his adoptive family and living a comfortable, easy life. However, he is now released back into the forest, and Boog, who is completely unaccustomed to the hardships of the wild, is determined to return to the city. But the appearance of Elliot, a black-tailed deer, changes his plans. Elliot, having lost one antler after being hit by a hunter, is tied up and being transported to town. After much hesitation, Boog finally rescues Elliot. This decision makes it impossible for Boog to smoothly return to his former life. 　　Elliot regards his savior Boog as a brother and follows him on his journey, luring him into the deep woods to truly "enjoy" the wilderness. Upon arriving in the forest, Boog realizes the conditions are far too harsh, nothing like the comfort of the city. Moreover, they make a mistake that leads the animals into a hunting zone. Faced with layer upon layer of danger, Boog's wild instincts are gradually awakened. He and the animals form an army to fight against their enemies, staging an intense battle to defend their home.