The Secret, starring James Nesbitt as double-killer Colin Howell, is a true crime drama that will make your skin crawl. Drawing on the real-life case of the Ballymoney dentist, the four-part series stars Nesbitt in what many still regard as one of his creepiest performances.
ITV first broadcast the BAFTA-nominated drama in 2016. The series revisits the disturbing story of a man whom the community once viewed as a “respectable dentist” and trusted “pillar of the community” — until the truth came out. Behind the façade, Howell plotted murder with his lover, Hazel Buchanan, a married Sunday school teacher, in a case that shocked Northern Ireland and the wider UK.
Viewers now have renewed reason to revisit The Secret. This week alone, two new documentaries shine a fresh light on Howell’s crimes. On Sunday (January 25), BBC Two airs Confessions of a Killer, the first part of a documentary that features confession tapes Howell recorded when he finally admitted to murder, alongside emotional testimony from those who knew the victims. Then, on Tuesday (January 27), ITV follows up with Killer in the House: The Murders of Lesley Howell and Trevor Buchanan, which reexamines the notorious double killing.
Is James Nesbitt drama about Colin Howell a true story?
The short answer is yes. The Secret firmly roots itself in a shocking true story. Colin Howell lived as a married dentist with four children and held a leading position within the Baptist community in Coleraine.
Away from public view, Howell conducted an affair with Hazel Buchanan, who was also married and taught Sunday school. Convinced that murder offered the only way for them to be together, the pair conspired to kill their spouses. Howell devised a plan to poison both victims with carbon monoxide and stage their deaths as a double suicide, making it appear that Lesley Howell and Trevor Buchanan had taken their own lives after discovering the affair.
In 1991, police discovered the bodies in a car filled with fumes in Castlerock. At the time, officers treated the deaths as a suicide pact. That explanation remained unchallenged for years — until 2009, when Howell, then a former lay preacher, walked into a police station and confessed.
On 29 January 2009, 18 years after the murders, Ballymoney dentist Colin Howell admitted to killing his wife, Lesley Howell, and Hazel Buchanan’s husband, Trevor Buchanan.
The case remains one of the UK’s most infamous double murders. Courts eventually convicted both Howell and Hazel Buchanan of killing their spouses. Howell now serves a life sentence for double murder, along with an additional five and a half years for multiple sexual assaults on anaesthetised female patients.
Who is in the cast of The Secret on ITVX and Netflix?
James Nesbitt takes centre stage as Colin Howell and delivers a performance that feels both unsettling and darkly compelling. Audiences know the actor for Cold Feet, Bloodlands and, more recently, Netflix’s Run Away.
Genevieve O’Reilly stars opposite him as Hazel Buchanan. Her previous work includes Andor, Tin Star, Glitch, Episodes and All Saints.
The supporting cast also impresses, with McDonald & Dodds favourite Jason Watkins appearing as Pastor Hansford. The series also features:
- Patrick O’Kane (Doctor Who) as Victor Buchanan.
- Stuart Graham (Harry Wild) as Dave Stewart.
- Glen Wallace (Hollyoaks) as victim Trevor Buchanan.
- Laura Pyper (Emma) as victim Lesley Howell.
- Jonathan Harden (Blue Lights) as DC Devine.
- Liam McMahon as DS Ferris.
Is The Secret based on a book?
The series adapts journalist Deric Henderson’s true crime book Let This Be Our Secret, which draws on extensive research into the case.
The book’s synopsis reads: “The killer dentist, his mistress, how they murdered their spouses – and how they almost got away with it.”
Where can I watch James Nesbitt as Colin Howell in The Secret?
True crime fans won’t have to hunt far.
The Secret streams for free on ITVX and is also available to Netflix subscribers.
How many episodes is it?
The Secret runs for four episodes, each lasting around an hour.
Episode one introduces Colin Howell as a prominent and respected member of the Baptist community before charting the beginning of a dangerous affair. Anyone familiar with the real case already knows where this story leads.
In episode two, Lesley inherits money and threatens to leave Colin, pushing him and Hazel to put their deadly plan into action far sooner than expected.
Episode three shows the pair briefly believing they might escape justice after a ruling in their favour, even as Hazel’s guilt begins to consume her.
In the final episode, Colin believes he can finally move on from his past — only to realise that his actions will not stay buried forever.
Reviews for The Secret on ITVX and Netflix
Critics widely praised The Secret, with many singling out James Nesbitt’s performance.
The Guardian’s Sam Wollaston wrote: “James Nesbitt leads a gripping true-crime drama where churchgoers are driven to wickedness by misplaced affections. […] It’s an equally scary portrait of the community – devout to the point that religion becomes a cover for serious evil.”
Den of Geek’s Louisa Mellor said: “Forget Jekyll and Bloodlands. In The Secret, James Nesbitt reveals everyday evil hidden beneath piety. The series is fascinating, psychologically complex and superbly acted.”
The Telegraph’s Gerard O’Donovan added: “James Nesbitt is credibly creepy in a devastating true-life tale. […] Nothing makes the skin crawl quite so thoroughly as seeing evil operate under the guise of religious righteousness.”
Read more: The best true crime dramas you can stream for free if you enjoyed The Hack