책이 사라진 날

This story has an extremely straightforward and simple plot perhaps a little too simple, but it makes it great for language learning.

The audiobook is just over an hour long, so I definitely recommend listening to it of you can. The only caveat there are the alien voices, I found them quite annoying, but at least the main characters's and narrator's voices are fine.

Language wise, while aliens are a main plot point, there actually isn't much alien related vocab, mainly 외계인 (alien) and 우주선 (spaceship). Other than that, there's a mix of vocab but generally not too uncommon, apart from some mimetic words here and there. The grammar is slightly harder, and a lot of the times the grammar points are abbreviated (니(까), 자(마자)), but sentences aren't that long either.