If someone doesn't know the lore, long story short:

"Christopher Robin left for boarding school and later for a college long time ago, forgetting about his forest friends. Pooh and friends went feral and lost their way without Robin's guidance. Sooner Christopher Robin goes missing in 100 Acre Wood."

So basically you are playing as Christopher Robin, a local man himself, and you have to find out, how you ended up in 100 Acre Wood and what happened since Robin left Pooh and friends.