The movie starts out in a barn with a mother cat who has given birth to kittens. One of the kittens is named Milo, and has a habit of being too curious and getting himself into trouble. He soon finds a pug puppy named Otis, some stuffed animals known as Winnie the Pooh, Piglet, Tigger, Rabbit, Eeyore, Kanga, Roo, and Lumpy, a human girl named Darby, and her dog Buster (along with their friends, Ash Ketchum, Pikachu, Misty, Togepi, Brock, Simba, Nala, Timon, Pumbaa, SpongeBob SquarePants, Patrick Star, Squidward, Sandy, and Mr. Krabs) and they become friends. When Milo is playing inside a box floating in the river, he accidentally drifts downstream. Otis and the others run after Milo. Milo goes on many adventures, escaping one incident after another. He encounters no fewer than three bears; escapes from the desolate, raven-infested Deadwood Swamp; steals a muskrat from a vulpine cache; follows a train-track to the home of a female deer, who shelters him; sleeps in an Owl's "dreaming nest"; stays for a while with a sow pig and her piglets; catches a fish, only to have it stolen by a raccoon; is mobbed by seagulls; and evades first the third bear, then a snake, only to fall into a hole. Otis, for his part, follows Milo throughout, usually only an hour behind and less than a mile out of range. Finally, the two catch up with one another while Milo is in the hole. Otis pulls him out by means of a rope. Milo and Otis are reunited, and soon find mates of their own: Joyce, a cat, for Milo; and Sandra, a pug, for Otis. After this they separate and raise children. They help each other's families to survive the harsh winter and find their way back together through the forest to their barn, living together.