A bulletin board falls on top of Stanley Lambchop as he sleeps, and he awakens to find that he is as flat as a fifty-dollar bill. At first, being flat is fabulous and Stanley finds he can do all sorts of unusual things like slip under doorways, fly like a kite, and even help a museum catch some sneak thieves. But being flat isn't all fun, especially when Stanley's young brother, Arthur, starts to get annoyed with his older brother's notoriety. Eventually, at Stanley's request, Arthur, armed with a bicycle pump, fills Stanley back to his regular size.