Premise: Comet in Moominland (Swedish: "Kometjakten" / "Mumintrollet på kometjakt" / "Kometen kommer") is the second in Tove Jansson's series of Moomin books. Published in 1946, it marks the first appearance of several main characters, like Snufkin and the Snork Maiden.
Hypothesis: Jansson had a previous book before comet in moominland