It’s the series that has millions of TV viewers hooked.
Who is the mysterious “H” and how many other twists and turns will there be in the plot before his or her identity is revealed?
One North Wales man could answer those questions, but he is sworn to secrecy because he has played a key part in the BBC production of “Line of Duty”.
The last two episodes of the engrossing series (March 28 and April 4) were directed by Gareth Evans, who was brought up in Prestatyn.
The 43-year-old, who works under the name Gareth Bryn, was already well established in the field, having been nominated four times as Best Director in the BAFTA Wales awards.
But “Line of Duty” is the most prestigious production he has been involved with as, like the previous five series, it has the nation hooked.
Gareth, whose parents Bryn and Paula, live in St George’s Drive, Prestatyn, attended Ysgol y Llys and Ysgol Glan Clwyd, and was interested in the theatre from an early age.
He was a member of the Young People’s Theatre at Rhyl Pavilion and then Theatre in the Community (TiC), his first big part being in Bugsy Malone in the Pavilion.
He gained a degree in the Liverpool Institute of Performing Arts (LIPA) and went on to appear in stage productions of the musicals Mamma Mia and Acorn Antiques before deciding to concentrate on film and TV production .
He directed episodes of the popular TV series “Last Tango in Halifax”, and it was through the contacts he made that he was invited to become involved with “Line of Duty”.
“It has been really interesting but the expectations were higher than on anything else I have done,” he said.
The series was filmed in Belfast but was interrupted by the start of the Coronavirus lockdown early last year.
Like most viewers Gareth’s parents have been keen to know how the series ends in two weeks’ time.
“But I told my mother that if I told her what happened I would have to shoot her,” he joked.
Gareth said that the show’s creator Jed Mercurio kept tight control of the whole production and that even the cast members were kept in the dark about some of the developments until the last minute.
In addition to directing he runs his own Cardiff-based production company Severn Screen which he has built up and now employs 90 staff. It has an excellent reputation, with credits for highly rated productions such as “Hinterland” and “The Pembrokeshire Murders” .
Gareth is currently working on a three-part series based on Val McDermid’s detective novel “The Distant Echo”, which is being filmed in Glasgow.
Friends and family have divided loyalties at 9pm on Sunday evenings as “Line of Duty” is directly up against the S4C psychological drama “Bregus” (“Fragile”), created by Gareth’s actor wife Mared.