Vengeance Is Mine (2)

Steve Jenner is killed at the opera, and the first theory is an accident of targeting: the killer meant Wilby's boyfriend Jonathan. Then Wilby kills himself, and the truth comes out differently. Jenner was Wilby's secret lover. And the killer knew things the police didn't. That gap in knowledge is the engine of the whole episode.

Kate follows the thread to the lawyer Jameson, who points at a retired forensic scientist, Dr Bannerman, as the link between the killings. Bannerman's wife is murdered before the trail goes anywhere useful. Every victim so far has a string attached to an old case, and the string keeps leading back to the same few people. Red pieces together the older story underneath: MacIntyre, Wilby and Bannerman were all tangled in the murder of Carl Brown, a case for which Brian Herd went to prison protesting his innocence. Duncan Warren worked that case too, and he now worries that his son Sam, or Anna the police clerk he's been seeing, will be next.

Red visits the dying Herd in prison, looking for any connection to the present killer. What he finds is a man still insisting he was innocent, and a mounting sense that the avenger's information is far too good. He doesn't get the link he came for, but he gets confirmation of something worse. The team lands on the conclusion none of them wants: the killer is inside the force. Waiting is not an option.

Lizzie Mickery, Robert Cooper and Boris Starling wrote it, David Richards directed. Frances Grey leads as Kate, with Alun Armstrong's MacIntyre, Gillian Taylforth, Emily Joyce, Tom Anderson, Paul Ansdell, Patrick Baladi, Greg Bennett, Dani Biernat and Ben Boorman in support.

It's the half of the story where the reckoning turns inward. The guilty and the innocent are both dying, and the only way out is somebody they work with.