In each hour-long episode, the show, which is a TV adaptation of detective novelist Agatha Christie’s book of the same name, explores and exposes the deep, dark secrets the Argyll family has kept hidden for years. It stars Bill Nighy as Leo, Anthony Boyle as Jack, Anna Chancellor as Rachel, Crystal Clarke as Tina, Christian Cooke as Mickey, Alice Eve as Gwenda Vaughan, Morven Christie as Kirsten Lindstrom and Luke Treadaway as Dr Arthur Calgary.
Writer and executive producer Sarah Phelps, who has done Agatha Christie adaptations before, said "Ordeal By Innocence" is ripe for TV adaptation because it has all the qualities of a show that is really going to draw people in.
“There is a family that is absolutely layered with some terrible, dark secrets. There is not one person in this family who doesn’t have a skeleton in their cupboard; who doesn’t have anything they don’t want someone else to know.
“Whether it’s a tiny secret, or a huge one that could topple an entire family. It’s a great premise,” said Phelps.
She said the actual process of adapting the book into a script started with an image in her head.
“When I began to think about "Ordeal By Innocence," I had this image of Magritte and a man in a homburg, wearing a dark overcoat. He looks like a normal man going off to work and yet he’s stepping out into infinity, which is genuinely disturbing.
“I was thinking so much about the 1950s. We tend to think of it as being rather a dull time - sunlit and innocent. You start to think about the rise in the number of people being prescribed sedatives at home; you start to think about the new advances in the way people are treated in psychiatric hospitals.
“You think about the way the government behaved; you think about the fact we had a new young Queen with a family, and the whole idea of motherhood and femininity has been weaponised,” she said.
Phelps set the main portion of the drama in the summer of 1956, which was deliberate.
“This is the summer before Suez, this is the summer before Hungary. So while we’re enjoying this rather red tooth and claw idyll of British life, you remember wthat the world is changing incredibly rapidly,” she said.
In the first episode, viewers are introduced to Arthur, who bring news that Jack was innocent as he was his alibi. He insinuates that someone else in the house must have murdered Rachel.
“In the book this character drops a bombshell, thinks to himself that everyone looks a little disturbed, wonders what’s going on, but then leaves the house and goes to London.
“When you’re writing an adaptation for TV, something has to happen which has drive,” said Phelps.
She wanted Arthur to have a story of his own which drives him forward.
“He needed to be able to deliver this piece of news that nobody wants to hear. It is really important that he is able to do something and make things right. I wanted to ask where he has been, why wouldn’t he be believed, and how does that propel his story and make him trust people he shouldn’t trust and not trust people he should.
“I liked the idea that he is a kind of prophet walking in from the wilderness to tell the truth,” said the executive producer.
Describing Rachel’s complex character, Phelps said that at the script read-through, they realised Rachel was not a monster.
“She’s a woman who had been betrayed and lied to; a woman who paints herself into this corner of brittle perfection. When I first started working on the show, I kept thinking, ‘What kills Rachel?’ Not who, but what, and what kills Rachel is the need to be perfect.
“I wanted to write this woman who appears to be impossible; who appears to be a real handful and who you’d have to put a gun to her head before she would admit what was wrong.
“Finding out that ticking time bomb of a secret is what explodes the whole drama,” she said.
"Ordeal by Innocence" is on BBC First on Wednesdays at 8pm. The show is also available on DSTV Catch Up.