In the peaceful town of Timberline, a 900-pound (408 kg) grizzly bear named Boog enjoys a captive, but pampered existence and spends his day as the star attraction of the town's nature show while at night living in the Garage (house) of park ranger Beth, who has raised him since he was a cub. One day, the sadistic hunting fanatic Shaw drives into town with a one-antlered deer strapped to the hood of his truck. After Boog frees him, the deer follows Boog home to find him sleeping in the garage. To wake Boog up, the deer throws rabbits at the window and introduces himself as Elliot. He tells him to be "free" from his garage captivity and introduces Boog to a world of sweet temptations he has never known.
One night, Bob and Bobbie leave their trailer to go skinny-dipping, leaving Mr. Weenie to guard the cinnamon buns they left on the counter. Boog and Elliot sneak into the camp and discover there's buns in trailer. Unfortunately, Weenie is guarding the door.
After falling head over hooves in love with Giselle, Elliot's road to the altar takes a slight detour when Mr. Weenie is kidnapped by a group of pampered pets determined to return him to his owners.
One spring morning, Boog awakens after hibernation and plans an annual guys trip to spend time with his male best friends. Unfortunately, Elliot has distanced himself from Boog since he had started a family with Giselle. They are now the parents of three children: Gisela, Giselita, and Elvis (with Boog now being the adoptive uncle). Boog is disappointed since everyone else wants to spend time with their families, which makes him go on the guys trip by himself with Dinkleman however, this soon leads him to a Russian traveling circus called the Maslova Family Circus.
The film opens with Elliot telling a campfire story about the legend of the Wailing Wampus Werewolf that lives in Timberline National Forest. Domesticated Boog is terrified by the story and decides to "chicken out" of their annual summer camping trip until he knows the werewolf is gone. Determined to help Boog overcome his fears, Elliot, Mr. Weenie and their woodland friends band together to scare the fear out of Boog and uncover the mystery of the Wailing Wampus Werewolf.
When Boog and Elliot discover an abandoned Summer Camp in the middle of nowhere, they embark on a brave new adventure of creating a safe and special place to live that welcomes animals of every kind. Under the leadership of Boog and Elliot, the Campers must all work together to help create their own slice of paradise in the middle of the wilderness and rediscover their inner wild.