The Lion, the Witch, and the Wardrobe - Chapter 17 - The Hunting of the White Stag

In which, the children go to the Castle at Cair Paravel, sit on the thrones and reign happily for many years and become adults. They forget about where they came from. Then someone brings them word of a White Stag and they go hunting and follow him to where they first entered Narnia, except they don't remember that. They follow until they are back in the wardrobe and return just as they had left without any time having passed. The professor tells them that they will some day return to Narnia, but from a different route.