First of all, I've long had an interest in Finnish, ever since I started writing science fiction stories with a Basque connection - an early story, "Last Things First," and my Locus-Award winning novel, The Silk Code. Finnish is a Uralic language, meaning it has more in common with Hungarian than other Scandinavian languages. Basque is not actually a Uralic, but has some similarity to the Uralic tongues in the way it creates lengthy word-versions rather than sentences made of shorter words, and, who knows, maybe Basque is in some way related to Finnish and Hungarian after all (but I don't want to get too science fictional here).
But it's fun to hear Finnish spoken, and the subtitles provide more than enough explanation of the story. In the case of Bordertown, it's actually four distinct though interrelated cases which Kari Sorjonen (very well played by Ville Virtanen) is either called upon to investigate or he can't help investigate because a member of his family is either a victim, suspect, or both.
Sorjonen is an unusual and memorable kind of detective. He has a brilliantly deductive mind - almost Holmesian - but his emotions are never too far from the surface. His wife and teenage daughter are commanding characters, as is Lena (strong acting by Anu Sinisalo), his partner, who comes to Finland by way of St. Petersburg. Indeed, the stories are sometimes as much about Russia as Finland, because most the action takes place in Lappeenranta (the Bordertown), close to the Russian border. Sorjonen has come to Lappeenranta from bustling Helsinki to find a bit of peace for him and his family, which of course he doesn't.
There's plenty of sex, perversion, and dark crime in these stories as befits a gritty Nordic Noir series. Highly recommended, especially in the summer, when the snow and ice of Finland look refreshing on the screen, whatever the seething criminality being enacted upon it.