Line of Duty fans were left scratching their heads last night as it was revealed Jo Davidson is related to a suspicious character.

Episode four was filled with drama from Superintendent Ted Hasting' forced retirement to DI Steve Arnott nearly being shot dead.

DSI Jo Davidson also received a warning from dodgy police officer Ryan Pilkington, with the tearaway trainee holding a gun to her head.

Receive newsletters with the latest news, sport and what's on updates from the Liverpool ECHO by signing up here.

However, at the end of the episode, Line of Duty was left on a cliffhanger as Arnott and DC Chloe Bishop presented Hastings with a file, that disclosed the identity of a blood relation to Jo Davidson.

While their identity was kept hidden, Hastings was left in utter shock.

Fans instantly started playing detective as they attempted to work out who the mystery relative is.

Some thought DI Matthew ‘Dot’ Cottan could be the relative, but actor Craig Parkinson was quick to shut the theory down.

DI Cottan was killed off in series three during a dramatic standoff with DC Kate Fleming.

However, responding to one fan, who tweeted: "@Cparks1976 Please let it be Dot. I’ll be so happy!", Craig denied he was reprising the role.

He tweeted back: "Yeah, it isn't."