A combination of Dirty Harry and William Peterson’s Manhunter.

Listen up. The best three hours of television you can watch. Ever.

It helps to have watched the first season (six episodes) and the second (four episodes), but it’s not absolutely necessary. All you need to know is that Scotland Yard Detective Chief Inspector John Luther is a tormented man, a brilliantly intuitive if frequently fatal cop, and a man who works very very close to the edge of the law in whatever he does. He also has a failed case in his past — a genius female serial killer who was as charming as she was sinister and just plain got away with everything because she was even smarter than Luther. Her escape haunts Luther’s career and reputation.

The caption above tells you a lot about Luther’s character but not everything. Season 3 opens with that as the central question: is he a good cop or a vigilante wearing a badge?

Sound familiar, generic, formulaic? It isn’t.

Trying to avoid spoilers, but there’s something epic about it. Idris Elba, who plays Luther, is listed as executive producer. It’s tempting to think he’s just cashing a ready made check based on the popularity of Seasons 1 and 2. He isn’t. It’s as if this set of four episodes is the completion of a trilogy. And a beautiful one it is. A battle of good versus evil in the starkest and ugliest of real world terms, with all the muddled shades of gray in between any literary purist could ask for.

How is it different? Unlike most dark Brit police shows, it isn’t written by a woman. The characters are well drawn, not stereotypical, and male, with the lone exception of Luther’s present love interest. The acting is superb, notably Idris Elba, Idris Elba, and, well, Idris Elba. And then everybody else.

The plot moves, as my wife pointed out, which she’s noticed doesn’t always happen in Prime Suspect, for example, or, ahem, Broadchurch. (Women do write. Why sales of Melatonin aren’t higher.) The over-arching villain, an internal affairs cop intent on taking Luther down, is as malevolent and immediately hate-inspiring as any I’ve ever seen on film, regardless of budget. (Finished watching the series tonight. And I still want to kill him myself.) But 98 percent of the time, he doesn’t even raise his voice. Did I mention the acting?

Guess I did. but I haven’t mentioned the writing. The best reason you need to watch. Good and evil matter, but the relationship between them is not, as so many dramas insist, a blur. It’s far more interesting than that. It’s more like…

No. Won’t say. You have to watch. On BBC America, Comcast on Demand, or Xfinity. No, I’m not being compensated by anyone. I’m finding you the best television series you’ve ever seen.

My wife told me I’m not allowed to mention theology. Why I haven’t.