The Book about Moomin, Mymble and Little My (Swedish: Hur gick det sen? Boken om Mymlan, Mumintrollet och Lilla My Literally: What happened next? The Book about Mymble, Moomintroll and Little My) is the fifth in the series of Tove Jansson's Moomin books and the first picture book, published in 1952. The book is famous for the cut out holes in its pages revealing a fragment of the next page. Canonically it explains why the Mymble and Little My is living in Moominvalley in the following book Moominsummer Madness.
The book is dedicated to Putte, likely referring to Tove Jansson's friend and once lover Putte Foch.
Moomintroll is bringing milk from the store back home to his mother, Moominmamma, when he meets the Mymble, who is searching for her missing sister Little My. Together the pair go looking for her. They crawl through a can to encounter Gaffsie fishing on the other side, the two get scared and jump through a rocky cave.
Suddenly they find themselves within the house of a large hemulen, who sucks them up in his vacuum cleaner. Luckily they are saved by Little My and escape through a window where they unfortunately land on a fillyjonk, who gets so scared she runs right through a page in the book and drops her dress.
The three follow a warming light inside a tree only to find it full of hattifatteners. Frightened, they rush out into a rain storm, and as the clouds part to reveal the sun they find they've finally arrived in Moominvalley.
To celebrate they plan to arrange a party, only to find that the milk Moomintroll has been carrying around the whole journey has gone sour and is stuck in the can. Moominmamma reassures them by stating from now on they will only be drinking cordial.
In 1993, the book was adapted into an animated short by Jaromir Wesely. Since then the book has been made into an interactive smartphone app and transformed into a giant sized playground on various exhibitions.