When Santa arrives at a child's house on Christmas Eve, does he go down the chimney feetfirst or headfirst? What if he gets stuck? What if there's no chimney? Maybe he slides under the door, as thin as a piece of paper? Or is it possible he pours himself through the tap? What happens once he's inside? Mac Barnett's iconic talent for earnest deadpan humour and Jon Klassen's irresistibly funny art honour this timeless question with answers both ridiculous and plausible, mounting in hilarity as the night continues.