That would be The Shield, which had Vic Mackey coldly executing a cop on his team, in front of his partners, in the very first episode, and ripped through seven seasons of harrowing, adrenalin-pumping story line. That's a lot to live up to for any new series, but Low Winter Sun is making a strong start.
Frank Agnew is not quite as hardened - as yet - as Vic Mackey, but he has all the trimmings. He's a good cop as far as catching criminals, but can't allow himself to be brought down by an Internal Affairs investigation. Like Mackey, Agnew is saddled with partners - or, at least, one detective, at this point, Joe Geddes - who is not quite as clever as Agnew, and whose interests are not quite the same as Agnew's either. Agnew has to therefore be on guard not only against Internal Affairs, but against Geddes, who in fact had to talk Agnew into murdering Geddes' corrupt partner McCann in the first place. The Lieutenant puts Agnew in charge of the McCann investigation, which on the one hand is a good thing, but also puts everything that Agnew does in greater view. This is the motif of the series: double-edged swords.
Low Winter Sun also has a gritty Detroit ambience - much like the short-lived Detroit 1-8-7 - and will likely benefit from Detroit's recent bankruptcy in the news. You certainly get a palpable sense of life in Detroit when Agnew walks out of his house, and you see a crumbled, abandoned house right next door.
So count me in as someone with high hopes for Low Winter Sun, as well as a weakness for the easy pun.