Tatort

If you have been for a longer time to Germany, I think it didn't escape your attention. Tatort which means crime scene in Englisch is a traditional Sunday evening to watch television crime serial. It starts after the news at 20.15 until 21.45. At least that is how it had been since the 70s when it started. Nowadays there are loads of reruns in the third programs and you also have the possibility to watch the series later on in the Mediathek.
There is a large twitter community which follows the weekly show and comments on it on #tatort, quite funny and interesting if you speak German. of course the serial itself is on twitter, too - @tatort.
On www.tatort-fundus.de you find more in depth information and  Tatort-Fans.de is the site for hard core fans with all useful information about the program and the twitter feeds.
Every episode is self-contained and often takes up newsworthy topics. This might be about practices in the pharmaceutic industries, political announcements or turkish migrants and their problems. The episodes take place in different cities in Germany and their surroundings.
I don't know if Tatort is also known outside the German speaking countries, but I have seen Derrick when I was in Italy. I mean, I have seen that they show it in Italy and apparently it has been quite successful all over the world. A fact that I don't understand because I would have rather bought the Tatort series.

I took one from 1975 - this is on Youtube where you will find several others and some also with Englisch Subtitles. I personally like best the ones from Münster, but everyone has their favorites. So just enjoy a little bit of German crime series for a change.
There is also a Tatort podcast which is made very well made.