Episode 6

AC-12's investigation finally exposes the truth: a vicious criminal gang has been running operations from inside the police force. The revelation lands differently on the two officers closest to the case. Steve Arnott is now convinced Lindsay Denton is innocent. Kate Fleming is equally determined to prove she played a role in the ambush. The team that has worked together all season is suddenly pulling in opposite directions. The episode is a finale in the truest sense: it closes arguments, not just cases.

The finale earns its length by refusing to rush. Arnott and Fleming's disagreement is not a plot convenience; it is the whole point. But if AC-12 cannot agree on who is guilty, then the corruption has done its work. The wider cast moves through the fallout, with Prasad, Cottan and Hastings dealing with the wreckage and Dryden's part in it becoming clearer. The truth is close at hand, which only makes it harder to hold onto. Every interview in the hour could go either way, and the show plays them all honestly. The episode trusts its audience to sit with two conflicting versions of the same woman, and the gamble pays off.

Jed Mercurio wrote it, Daniel Nettheim directed. Keeley Hawes and Martin Compston carry the argument at the heart of it, with Vicky McClure's Fleming refusing to give ground. Craig Parkinson's Cottan, Adrian Dunbar's Hastings, Sacha Dhawan's Prasad, Jo Donnelly's solicitor, Mark Bonnar's Dryden, Charlotte Spencer's Carly Kirk and Bennett Warden's Vicar fill out the final act. The interrogation of the truth here is the show at its most patient.

There is a particular strength to a story that lets its investigators disagree in good faith. The series has always known that the truth is not the same as agreement, and this episode puts that knowledge on screen. Somebody is right and somebody is wrong, and neither side gets to find out cheaply. The season ends with a verdict, but the damage is still being assessed. The cost is the point, and the ending lands it.