Mother. Of. God.
Before it aired, episode four of the sixth season was hyped as the best Line of Duty episode since the show first hit our screens in 2012. Martin Compston said "if we deliver it has the potential to be a classic." And boy, did they deliver. A shootout with the OCG, Steve pulling off a shot most Call of Duty addicts would be proud of, a murder in prison, Ryan putting a gun to Jo's head, and a big fucking cliffhanger at the end.
Focusing on the very end of the episode, which had thousands of viewers rewinding their televisions to see who the photograph on the piece of paper was (it's Jo Davidson, as if they would leave the big reveal there in the age of pausing TV), all the discussion in the aftermath surrounds who this mystery relative of Jo Davidson could be.
By the looks of social media, viewers are going full Charlie Kelly, mapping out every plot line from all the way back in the first season to work out who it might be, and while Jed Mercurio will probably catch us all by surprise, there seems to be a broad consensus that it is John Corbett.
Corbett was deep undercover with the OCG in the fifth season, before he had his throat slit by Ryan Pilkington. Steve Arnott and Ted Hastings both still have (very different) relationships with Corbett's widow, Steph, which will only complicate this already complex plot even further.
The main piece of evidence pointing towards John Corbett relates back to a previous episode in this series. After Jo's row with Farida, during which she told her she didn't have a family, she later throws a glass at a photograph in her bedroom. Freeze frames of this scene show the photo to contain a younger Jo Davidson with what appears to be her mother, as seen here.
Many viewers have pointed out that this could be Anne-Marie McGillis, Corbett's biological mother who went missing in 1989.
McGillis was also a key informant for Hastings during his time in Northern Ireland.
The photos alone are a strong case for Corbett being Jo's brother, and fans appear convinced.
https://twitter.com/heyitshann/status/1381355903102943233
https://twitter.com/JWRobbo/status/1381353800582238209
https://twitter.com/JoshuaTindall/status/1381351389415227398
https://twitter.com/lesleyanne_d/status/1381352327458779139
There are other suggestions that the mystery relative could be Tommy Hunter from the first season, given the fact both he and Jo are Scottish, as well as the golf related clues dropped in throughout this season, and Jed's current tendency to hark back to the show's origins. But right now, Corbett seems like a safer bet.
