Where is my bear? asks a little girl as soon as she comes home from school. But hes missing! Where could he be? She sets off to find him, knocking on the door of each apartment in her building. As she climbs higher and higher, she meets a strange bunch of people and objects, makes new friends, sees strange sights but what about her bear? Will she find him? A childs quest for her lost toy turns into a wonderful adventure that unfolds, literally, fold after fold into a building full of life. Knock! Knock! is book architecture at its inspired best.