The Secret opens in the jubilant, happy-clappy setting of a Coleraine Baptist church.
Dentist Colin Howell, played superbly by Ulster-born actor James Nesbitt, is the buckle in this tightly fastened Bible belt.
Leading the congregation in cheery Christian song, he oozes piety and respectability.
And yet, as we all now know, this God-fearing pillar of the community, would go on to commit adultery, help his lover have an abortion and then mastermind and execute a double murder.
Speaking at the screening James Nesbitt described Howell as ‘‘a very complicated man’’, adding ‘‘it’s a painful story, it’s a story about a place where I come from.’’
He added: ‘‘It would have been easier if he had been incredibly charming, with Colin it was a bit more complicated because he wasn’t.
‘‘I think some people didn’t warm to him and there was a banality almost to him as well.
“I’ve talked to many people who will have known Colin. I’m from Coleraine. He lived opposite my sister, they had the same cleaner, my sister went to some of Lesley’s coffee mornings, which I only found out recently.”
The drama is based on the book, Let This Be Our Secret, by Deric Henderson, the former Ireland editor of the Press Association.
It is the real-life story of how Howell and his lover, Coleraine Sunday school teacher Hazel Stewart, who then went under her married name of Buchanan, became embroiled in a passionate affair and killed their spouses, Lesley Howell (played by Laura Pyper) and Trevor Buchanan (Glen Wallace) in 1991.
The bodies of mum-of-four Lesley and policeman dad-of-two Trevor were found in a car filled with fumes in Castlerock in May 1991.
Howell and Stewart conspired to make the deaths of the couple look like a suicide pact.
For almost 20 years they lied to families, police and friends until Howell confessed in 2009.
The first two scenes of this four-part series are set against the backdrop of a close-knit suburban community, of bungalows and manicured lawns, with the church and the pastor’s influence at its core.
Nesbitt’s portrayal of ‘driller killer’ Howell is superlative. He is creepy, insincere, and utterly compelling to watch.
Genevieve O’Reilly, who plays Hazel and bears an uncanny resemblance to the blonde-haired, angelic-looking assassin, is equally excellent as Howell’s biddable accomplice.
In a disturbing and poignant scene, she is seen calmly arranging pot pourri in a bowl in her bedroom a short while after her husband’s murder there.
The Secret, written by Bafta-winner Stuart Urban and directed by Nick Murphy, is an exploration of how wickedness and evil can flourish under the cover of religion, of how charm and control can have murderous and catastrophic consequences.
It is a gripping, powerful depiction of a horrendous crime.
Watching it, it is easy to forget that it’s based on a true story, that it’s ‘lead characters’ are only a few miles away behind bars, that the friends and families of Lesley Howell and Trevor Buchanan are still doubtless grieving and raw. From this perspective, many will find The Secret uneasy viewing.
*The Secret will begin on UTV on Friday, April 29