This is another of those books which has been sitting on my TBR bookcase for a while, so I'm feeling quite pleased with myself for actually reading them - if I recall correctly, Not Before Sundown (which has also been published as Troll) was initially recommended to me at the London WorldCon when there was a panel on European SFF.
Basically, Not Before Sundown is the story of Angel, who works as a photographer and who stumbles across two local teenagers kicking hell out of someone when he's on his way home from a bar. When Angel intervenes, he discovers that the 'someone' is actually 'something', a juvenile male troll, and takes it home - this is a Finland where trolls exist as part of the larger wildlife of the country, as well as still playing a part in mythology, but are very rarely seen. Alongside trying to care for the troll, who he calls Pessi, Angel is also dealing with a number of relationships, both sexual and otherwise, as well as meeting his creative deadlines.
The book is told from various points of view, as well as with excerpts from local lore and scholarly works about trolls; often shifting points of view would annoy me but it actually works quite well here. What doesn't work quite so well for me is two things: firstly, the inference that Angel is only looking after Pessi because of some kind of sexual attraction to him (which could be an issue with the translation, of course), and secondly the fact that the book just stops with no resolution for any of the characters. I've seen comments elsewhere criticising the translation and I would agree that at times the language choices are a bit clunky, so with all that in mind I've given it 3 stars.