This is part of Germany's "heiter bis tödlich" (cheerful to deadly) series of the state controlled ARD TV channel.
This installment is located in the North of the country, namely the city of Lübeck (appr. 23.000 inhabitants, located at the "Ostsee" = the baltic sea). The first & second seasons were mainly "cheerful" but still dealt with "murder", afterwards it became more & more bleak & realistic & improved a lot over the "cheerfulness" of the earlier episodes. Most actors (especially Naujoks) are very good & the series even "survived" the introduction of the (always) godawful, non-actress Proschat Madani in a supporting role.