Episode 1

A criminal is shot dead by an armed response unit led by Sergeant Danny Waldron, and on paper it looks clean: self-defence, hostile subject, all procedures followed. AC-12 take a look anyway, and the cracks start to show. The evidence suggests something more deliberate than a man acting on instinct, and the question becomes whether the unit is hiding a cold-blooded murder. It is the kind of question that does not get asked politely. The unit tells its story well, which is exactly what makes it worth looking at. It opened the third series in March 2016 with the question the show would keep asking: how far can the official version of events be trusted when the officers involved are the ones telling it?

The episode does the patient work of pulling the official story apart. Waldron's team is put under scrutiny, and the inconsistencies start to multiply. Every officer has a version of events, and the versions do not quite match. Arnott and Cottan push from AC-12's side while Hastings keeps the wider picture in view, and the tension comes from watching professional men try to hold a story together that is coming apart at the seams. The interviews are long, and the silences are longer. The show has always understood that the most interesting part of a case is the moment the official version stops holding.

Jed Mercurio wrote it, Michael Keillor directed. Daniel Mays is excellent as Waldron, all coiled discipline and barely hidden strain. Martin Compston's Arnott, Craig Parkinson's Cottan and Adrian Dunbar's Hastings lead the investigation, with Will Mellor's Kennedy, Shaun Parkes's Reynolds, Lisa Palfrey's McAndrew, Arsher Ali's Bains, Leanne Best's Brickford and Shane Gately's Murphy around them. It is a strong cast, and the episode uses every one of them.

The episode is about how thin the line is between procedure and murder when the people holding the guns decide where it goes. The question itself is old, but the show asks it with unusual patience. The team's story will not survive contact with the truth. The only question is how much damage it does on the way down, and the season has time to find out.