One of the oldest still running German cop shows on air since 2003, available both on ZDF Neo and on DVD with annual release cycle which makes it quite accessible. Witty writing with dark sense of humor and mostly balanced characters of both cops and robbers. There's a formula for every episode where all of the events are interconnected and should be solved during the length of the shift. Not entirely realistic show, but definitely entertaining one and giving the longevity, always easy to watch.

Earlier, vintage episodes are the most interesting ones in my opinion. There are repeating character tropes in the second season, but overall quality is good. The setting is always the same which makes it even more interesting as you can see how the city and night scene changes over the years.