The long-awaited drama starring James Nesbitt as respectable dentist turned double murderer Colin Howell aired on Friday night - with many taking to Twitter to offer their thoughts.
The first in the four-part drama series about Colin Howell and Hazel Stewart who murdered their partners in 1991 was on UTV.
While there were a few to tweet criticism, in the main the reaction was good with many praising James Nesbitt for his portrayal of the good dentist and faithful Christian who would turn to murder.
Am I the only person who finds Jimmy Nesbitt disturbing whatever he's in? #TheSecret— S C Richmond (@sc_richmond3) April 29, 2016
The number of people watching #TheSecret who think the title refers to an affair, shows how few news stories from here, make it over there.— Laure James (@LaureJames) April 29, 2016
'The Secret' with james nesbitt was a really good show.People truly are awful.— Christopher (@ghostdance3000) April 29, 2016
@barrabest Thought I'd see you as an actor on The Secret or was it you in charge of getting the windeys steamy in the car?!— Netmums Jill (@netmumsjillh) April 29, 2016
They didn't really show how their relationship/affair developed at all #TheSecret— Caroline Lee (@Lady_Carolina_) April 29, 2016
What a twisted man he is!what if we could end their suffering? I think you find your causing it pal! #TheSecret— Donna le p (@DonnaLePrev) April 29, 2016
@BelTel Jimmy is great, as always.— Gary McAllen (@garymcallen) April 29, 2016
Some quite odd depictions in #TheSecret . But still an horrific story. Feeling for the fine folk of those congregations.— Mark Thompson (@MarkThompDesign) April 29, 2016
@BelTel poor casting. No chemistry between the 2. especially with Nesbitt— Jenny Wilson (@jenailsa) April 29, 2016
Half an hour has passed n I'm already gripped by #TheSecret this is already looking fantastic— Samantha Friar (@friar_samantha) April 29, 2016
#TheSecret making one hour of a Friday night bearable— Aisling McGroggan (@AislingMcGro) April 29, 2016
OK, lads, could do without the singing. Nesbitt singing is worrisome, unless it’s The Hobbit. (And now wet Nesbitt, sweet lord.) #TheSecret— Anna (@travellinwriter) April 29, 2016
#thesecret I know what happens in the end (he was my dentist IRL)— Sam Campbell (@SC3L) April 29, 2016
The Secret tells the real-life story of how Coleraine Sunday school teacher Stewart and her lover Howell turned into murderers.
Howell and Hazel, who then went under her married name of Buchanan, became embroiled in an affair and plotted to kill their spouses, Lesley Howell and Trevor Buchanan.
The Secret tells the dramatic story of how the Ballymoney dentist and lay preacher gassed his wife and Stewart's husband to make their deaths look like a suicide pact.
For almost 20 years they lied to families, police and friends until Howell confessed in 2009.
The couple each received a life sentence for their roles in the Castlerock murders.
Nesbitt appears alongside Genevieve O'Reilly, who plays Hazel.
Dublin-born actress Genevieve (39) says that when she read the script she was immediately drawn into the Stewart/Howell web of deceit and lies, and ultimately murder.
She said: "We are not working with fiction - this is the truth and there are real lives and real people involved here."
While there has been a lot of anticipation around the programme, some commentary and opinion has voiced that it is being aired too soon.
Kevin McAuley, now a freelance photographer first met Trevor in 1986 as the police officer and his wife, Hazel, were transferred from Omagh to Coleraine.
He said: "There are many people who knew the victims and the killers - leaving aside even their families - and they may be upset that this drama is being screened.
"However, people have to live in the real world and accept that a television series has been made. I don't have any issue with this drama, but others may have a different opinion."
The drama is based on the book, Let This Be Our Secret, by Deric Henderson, the former Ireland editor of the Press Association.
The first episode airs tonight (Friday April 29) at 9pm.
She is playing one of Northern Ireland's most notorious murderers but actress Genevieve O'Reilly admits she had no idea who Hazel Stewart was before she was offered the part in The Secret.
It was unquestionably the trial of the century in the wake of Northern Ireland's crime of the century - a ruthless double murder disguised by a heartless Ulster killer as a double suicide - but veteran journalist Deric Henderson found it difficult to interest newspapers in Britain in the horrific exploits of dentist Colin Howell and his mistress and accomplice, Hazel Stewart.