The country is waiting in anticipation for the final episode of Line of Duty to air and there's one question on everyone's lips: 'who is H?'
You can always depend on Martin Compston to tease fans and now he's dropped a major clue that Mark Bonnar - who plays Mike Dryden - could be unveiled as 'H' in the highly-anticipated season finale, reports the Daily Record.
The elusive "fourth man" has been at the centre of the show's mystery, known to have links to both the OCG and high ranking police officers, everyone from Ted Hastings to Joanne Davidson has come under suspicion.
The Scottish actor, who plays DI Steve Arnott, shared a cryptic hint with fans where he hinted at which cast member may finally be unmasked as H on Sunday night's episode.
Taking to Twitter, Martin shared a video clip with the caption "The ABC Song..." as he teased viewers.
In the clip, he recounts the alphabet and says: "A, B, C, D, E, F, G."
But before he reaches 'H', Mark Bonnar, who plays Mike Dryden in Line of Duty, pops up on screen.
"Oh, hello Mark", Martin says in the clip before laughing.
Fans were quick to speculate over the cryptic message and took to the comments.
One wrote: "You are such a tease DI Arnott!"
Another commented: "I thought he was dead? Have you just dropped a spoiler?"
A third wrote: "Ehhhhh he just stopped before he said H!!!!!!! He popped up on H!!!!!!!"
Mike Dryden, the former Deputy Chief Constable, was last seen resigning from his post for perverting the course of justice in series two.
Fans will remember he was outed as having embarked on an affair with DS Lindsay Denton (Keeley Hawes) before pressuring her into having an abortion.
He then used then OCD leader Tommy Hunter's sex trafficking victim Carly Kirk and authorised the operation that got Hunter murdered, which Denton was then framed for.
But his official charge was for perverting the course of justice for lying about his wife's speeding ticket, and he was forced to resign from the police force.
Fans have previously speculated he could be related to Jo Davidson after it was revealed her DNA matched someone on the Police National Computer.
Due to their Scottish links, viewers claim he could be the mystery blood relative.
Line Of Duty fans will soon find out exactly who 'H' is in what promises to be a dramatic season finale on Sunday.
