One evening in autumn, the energetic Too-ticki brings a strange guest to the Moomin House: the shy Ninni has been frightened so many times in her life that she became paler and paler and finally invisible. Now the friendly, polite Moomins are supposed to make her visible again. Piece by piece they succeed - only Ninni's face remains blank. Ninni can neither play nor get angry, as the little Mü is horrified to discover. And she doesn't understand jokes either. A hopeless case? At least until the day when Moomin's father has the fateful idea of playing a trick on Moomin's mother ... One of Tove Jansson's most profound stories, entertaining, humorous and with an eye for the essential.