Line of Duty's sixth season will come to a dramatic conclusion on Sunday evening as the search for 'H' will come to an end.
H is a corrupt police officer responsible for a mass conspiracy and the police drama has pulled in millions of viewers as people speculated on the identity of the mystery character.
A seventh series of the hit drama has not yet been announced.
Earlier this week, a YouGov poll found viewers of the programme think Chief Constable Philip Osborne is the most likely candidate for H.
A total of 22% of viewers believed him to be the mystery officer anti-corruption unit AC-12 are hunting for in the series.
Detective Chief Superintendent Patricia Carmichael was the second most popular choice after being selected by 19% of viewers.
Line Of Duty's penultimate episode earned an average of 11 million viewers and 51.7% of the audience share, according to the broadcaster.
On Friday actor Martin Compston, who plays DI Steve Arnott in the series, told The Jonathan Ross Show that Line Of Duty will not return for future series "just for the sake of it".
He added the "natural story arc that we've been on for the last six years (is coming to an end)".
Line Of Duty airs on BBC One at 9pm on Sunday.
