In the tranquil town of Timberline, a 900-pound grizzly bear named Boog has his perfect world turned upside down after he meets Elliot, a one-antlered mule deer. After Elliot messes up Boog's nature show, they end up tranquilized by Boog's owner Ranger Beth and then her friend Sheriff Gordy tells her to release them into the Timberline National Forest before open season for only 3 days. But when hunting season comes, it's up to Boog and Elliot to rally all the other forest animals and turn the tables on the hunters. In the end, Boog decides to stay in the forest and says goodbye to Beth (who came back to take Boog home).
One fine spring morning, Elliot gets all prepared for his big wedding with Giselle. But little do they know, Bob and Bobbie have left a trail of doggy treats in the forest for Mr. Weenie to follow, which he does and he ends up getting taken back to his original home by his owners. Elliot sees this, tells the story to Boog and the others, and they all make a mission to go save their friend before he gets turned back into a pet. In the end, Mr. Weenie decides to remain a pet again and go live with Bob and Bobbie and the other domestics.
Boog wakes up early in his cave one spring morning and gets ready for the new guys' trip to start spending more time with his male friends. Unfortunately, they all decline because of family obligations; this makes Boog feel bad and take Dinkleman with him on the trip himself, only to discover that it's not a guys' trip with only one guy. He then stumbles upon a poster of the Russian Maslova Family Circus, where he meets a devious lookalike named Doug, his llama friend Alistair, and a skilled girl bear named Ursa (whom he falls madly in love with). When Doug tricks Boog into letting him switch places with him, Elliot and the wilds find out about this and set out to rescue their beloved bear friend (especially as the circus is going back to Russia sooner or later), with Elliot being the leader once again. In the end, Ursa decides to live with Boog and his friends since he doesn't want to leave her or Elliot.