After a long and eventful life, Allan Karlsson ends up in a nursing home, believing it to be his last stop. The only problem is that he's still in good health; and in one day, he turns 100. A big celebration is in the works, but Allan really isn't interested and decides to escape. He climbs out the window in his slippers and embarks on a hilarious and entirely unexpected journey, involving, among other surprises a suitcase stuffed with cash, some unpleasant criminals, a friendly hot-dog stand operator and an elephant (not to mention a death by elephant). It would be the adventure of a lifetime for anyone else, but Allan has a larger-than-life backstory: Not only has Allan witnessed some of the most important events of the twentieth century, but he has actually played a key role in them.