Episode 1

AC-12 investigates DCI Jo Davidson's apparent mishandling of the murder of investigative journalist Gail Vella. Jo has received new information about where a suspect might be, but on the way to the raid she spots an armed robbery in progress and stops the convoy. The detour costs her dearly: AC-12 start asking why she did it, and the answers are not flattering. The dead journalist has been waiting for justice for a long time, and the case has gone cold in all the wrong ways.

The episode is still dealing with the fallout from the Corbett investigation, and that shadow makes everything harder. The unit is jumpy, the hierarchy is watching, and Jo is the most enigmatic adversary they have faced in a while. The question of what she is hiding, or whether she is hiding anything at all, drives the whole episode. The cold case of Vella's murder is the frame, and Jo is the picture. Nothing about her is easy to read, which is exactly the problem. The team that came through the Corbett affair is not the team it was, and the episode lets that show.

Jed Mercurio wrote it, Daniel Nettheim directed. Kelly Macdonald makes Jo a genuinely hard read, all composure and private calculation, and the mystery of her is the episode's engine. Martin Compston's Arnott, Vicky McClure's Fleming, Adrian Dunbar's Hastings, Anneika Rose's Jatri, Perry Fitzpatrick's Lomax, Shalom Brune-Franklin's Bishop, Nigel Boyle's Buckells, Patrick Buchanan's Briggs and Ben Rose's Kilorgan complete the cast. It is a strong opening cast, and the show slots the new faces in without a wobble.

The episode knows how to introduce an adversary, and Jo is introduced with a careful lack of clarity. The detour to stop the robbery is the kind of detail that could be heroism or cover, and the show refuses to say which. But the threads connecting to Vella's death run deeper than a simple mistake. That much is clear. The mystery of Jo is the hook, and the hook is set deep. The rest is the season's job.