Manny, Sid, and Diego discover that the ice age is coming to an end, and join everybody for a journey to higher ground. On the trip, they discover that Manny, in fact, is not the last of the woolly mammoths.
Wilbur the pig is scared of the end of the season, because he knows that come that time, he will end up on the dinner table. He hatches a plan with Charlotte, a spider that lives in his pen, to ensure that this will never happen.
Boog, a domesticated 900lb. Grizzly bear finds himself stranded in the woods 3 days before Open Season. Forced to rely on Elliot, a fast-talking mule deer, the two form an unlikely friendship and must quickly rally other forest animals if they are to form a rag-tag army against the hunters.