Line of Duty, season 6 episode 6, BBC One review ★★★★★

Well, that’s another exciting question answered: the two shots landed, cleanly, on Ryan’s chest like a vampire bite. The lack of dripping or gushing blood is curious. It happened (or, rather, didn't happen) before in episode five, when two OCG members were shot dead and left no splatter. Is this part of the story? Are these criminals still alive somewhere?

Sorry. Line of Duty inspires and encourages a conspiratorial mindset in every facet of the series – even the filmmaking. The absence of blood is still weird, though…

In any case, as far as we know, PC Ryan Pilkington (Gregory Piper) is gone for good and so is his knowledge of the OCG. It’s a devastating blow to AC-12’s investigation. DI Kate Fleming (Vicky McClure) kills him and doesn’t take DSU Jo Davidson (Kelly Macdonald) into custody, choosing instead to go on the run.

Intensely executed by director Jennie Darnell, this opening section spins into a car chase of confusion and deception. It's another cracking action scene, and shows Kate’s hitherto unseen skills at the wheel. The nature of her relationship with Jo is still ambiguous (platonic? romantic?) but given the saving words in Jo’s interrogation later, there’s clearly a strong, unexplained connection between them.

Now, it’s Kate’s turn to be in prison: the last of the former AC-12 team to have that hypocritical honour (Steve in season three; Superintendent Ted Hastings in season five). When she’s cornered by an army of police officers, she looks on the verge of a shooting spree – gripping her gun as Steve approaches.

Kate has an absorbing uncertainty about her; she's difficult to predict. That's a rare quality for a character who’s been on TV for nearly 10 years, and a testament to Jed Mercurio’s knack for well-written surprises.

But the star scene of this episode is the interrogation, which unfurls across an intense 29 minutes and 22 seconds. That makes this uninterrupted session the longest Mercurio has ever written for Line of Duty. The extended dig for the truth is still breathlessly exciting, despite the dreary admin and constant citations – respected, clearly, by Ted's stimulated eyebrow.

Even better: both Ted (Adrian Dunbar) and DCS Patricia Carmichael (Anna Maxwell Martin) question Jo together. The two strongest forces in Anti-Corruption unite with seething teeth.

Mercurio crushes those minutes via the shocking revelations reluctantly leaving Jo’s mouth, often punctuated by the classic No Comment formula. But Steve delivers the gut-puncher: telling Jo that her criminal uncle, Tommy Hunter, is also her biological father. It’s a gruelling sequence; Jo's complete family history is the stuff of nightmares. And yet, she still doesn’t reveal the identity of who she thought was her father. This critic’s money is on Marcus Thurwell (James Nesbitt).

Talking of Thurwell, he proves to be another dead end in a night-vision scene of Sicario-like suspense. AC-12 watch the body cams of Spanish authorities attempting to capture Thurwell, but only find two bodies in a room full of flies. Another wound to the investigation, and you feel Ted’s pain (‘there’s only so much a man can take!’).

Considering that the AC-12 victories are few and far between, hope may be running out – particularly as the original unit is breaking apart. Ted’s being forced into retirement, Steve’s about to be fired for avoiding a drugs’ test, and Kate is in the slammer. Will Mercurio tie up these hopeless knots? Maybe. But considering the build-up to Kate’s death in episode five, someone close could be chopped.

Line of Duty continues Sundays at 9pm on BBC One