THERE is a moment in the first episode of new Sunday night drama The Cry when Jenna Coleman’s character, a washed-out new mother weighed down with baby, buggy and bags, struggles up the steps of her tenement flat.

“I watched it thinking – my God, that was my life,” marvels Glasgow author Helen FitzGerald, upon whose novel the new series is based.

“My daughter was born in November, we lived in a top floor flat, and that scene just took me back to when I was exhausted, not getting any sleep, being afraid of my new baby.”

The Cry, which was filmed in Glasgow and begins on BBC1 tonight, is the story of Joanna (Coleman) and Alistair (Top of the Lake’s Ewan Leslie), a young couple from Glasgow who travel to Australia to fight for custody of Alistair’s daughter from a previous relationship.

After an excruciating flight – an uncomfortable scene which will strike a chord with anyone who has ever travelled any distance with a fractious newborn – the unthinkable happens, and the baby is abducted.

What follows is a gripping and decidedly unsettling story of a young mother in crisis, trying to cope with every parent’s worst nightmare.

Australian-born FitzGerald, author of a string of successful thrillers, is certain the roots of her novel – which has been adapted by screenwriter Jacqueline Perske – lie in her experience of new motherhood.

“When I look back on that time now, I know what it was,” she says. “I’ve just been through a period of serious anxiety and depression, so now I understand what was happening to me then.

“I never coped very well with Scottish winters, so I always booked a flight to Australia in January.

“Between having Anna and going to Australia, I was having problems breastfeeding, we weren’t sleeping – I’d see other mothers, women I’d met at my antenatal classes and think, how is she doing that? How did she get that baby into the car and park in a multi-storey and get the pram into the shops?”

She pauses. “It’s a common sign of post-natal depression, the feeling that everyone else is coping. I was obsessed with child-rearing books too, desperate to get it right.”

The turning point for FitzGerald came, she says, when Anna – who is now 21 – was nine months old.

“We were in the back seat of the car, and I was doing that thing of – don’t look at the baby, in case she starts to cry again,” she recalls. “And then I turned around and looked at her and she was just sitting there, smiling at me. That was the moment – the one that happens for most mothers at the birth? It happened to me right then.”

The Cry, which was published in 2013, was also influenced by FitzGerald’s interest in two high profile child abduction cases of recent times.

FitzGerald, now 52, was a teenager in Australia in 1980 when Lindy Chamberlain was wrongfully convicted of murdering her nine-week-old daughter. She claimed she saw a dingo leave the tent where Azaria was sleeping, during a family camping holiday. The case was highly publicised, and Chamberlain was convicted and jailed. After new evidence was discovered, she was released and her conviction was quashed in 1988.

In 2007, four-year-old Madeleine McCann vanished from a holiday apartment in Portugal’s Praia da Luz, sparking another high profile media campaign in which accusations were levelled at Madeleine’s parents, Kate and Gerry.

“I saw Lindy speaking on television to the McCanns, giving them support and I thought – what a terrible community this is, what an awful thing by which to be bound together.”

She adds: “I have always believed both of them. But thinking about their cases made me wonder – what kind of couple would get away with something like this? What would have to be going on behind the scenes in that relationship?”

In both cases, says Fitzgerald, media interest focussed on the mother.

“Does anyone remember Mr Chamberlain’s name?” she says, wryly. “Lindy was incredibly naïve and open and just had no clue, and she got slaughtered by the media. Her case was really the first example of trial by television.

“Women are always the target, especially when babies are involved. No matter how much we talk about parental or gender equality, that’s what happens.”

FitzGerald’s original ambition was to write for film and television, so to see her work finally on screen has been hugely satisfying.

“I tried scriptwriting and got nowhere, did some books instead, and that worked out quite well,” she laughs, understating hugely the success of her bestselling books, thrilling and often chilling contemporary tales which include Dead Lovely, Viral, My Last Confession and The Donor.

FitzGerald wrote The Cry in 2013 and it was subsequently longlisted for the Theakstons Old Peculier Crime Novel of the Year.

Finishing the book it was a relief, she recalls.

“Joanna’s head was a tough place to be,” she says. “Originally I planned to write the whole thing from her point of view but I couldn’t do it.

“I was overwhelmed with happiness when I saw the first episode. I was shaking for what felt like days.”

She adds: “It was hard to let it go, but Jacqueline was fantastic. We spoke about what we both liked about the story, and then I understood she needed to get on with the process without my interference, and that was fine.”

The idea may have taken root years before, but the themes of The Cry are contemporary – trial by media and social media; pressure on women; the myths and truths of motherhood.

“There is a great deal of pressure on young mothers,” says FitzGerald, simply. “Everything they do is under the spotlight. Lindy had it hard enough, but everything is so capturable now.”

FitzGerald describes herself as a “sick kid who read a lot”, 12th child in a family of 13, growing up in Victoria in a house built by her engineer dad.

“My mum was a literature teacher, and she always encouraged me to read,” she says. “I wrote diaries –terrible diaries – and stories from a young age.

“I was very glad to marry a writer, who understands what it’s like.”

Fitzgerald lives on Glasgow’s south side with her husband, screenwriter Sergio Casci and their two children, Anna and Joe.

When she moved to Scotland at first, she got a job working in a unit for high risk offenders in Edinburgh, before moving to Glasgow, where she worked at Barlinnie.

For the last 10 years, she has been a criminal justice social worker, based latterly in the community in Paisley, although she has recently taken a step back from her day job.

“A friend said to me recently my writing and social work are actually quite similar – you get to know somebody, work out why they have problems and fix them – or make them worse,” she says. “People in crisis, moral dilemmas…she has a point.

“Spending a day inside Joanna’s head was sometimes as emotionally demanding as spending a day inside a prison.”

Last year, FitzGerald left her job, she says, to “calm down”.

“I felt like I was living my life at 40 million miles an hour,” she says. “When I looked back at life before 40, it was all about going out every Friday and Saturday night and if you weren’t doing that, it was pointless.

“I had to change and I am changing my ways.”

She pauses. “Will it change what I write? I don’t know,” she says, slowly. “I have certainly changed how I write. I used to sit down and write 3000 words a day, easily, but now it’s much more intense and particular, like I don’t want to waste even one word.

“I know this comes from having had depression. Someone once said you can’t write your way through a nervous breakdown, but I think I just have.”

The last 18 months have been difficult, she admits.

“I watched a lot of television,” she says. “Some days I couldn’t even get out of bed. The Sex and the City boxed set was my safe place. I watched it again, and again – it was meditative almost, just on in the background, reassuring me.

“I felt like my bed was wet concrete, that I could sink into it and disappear.

“The doorbell ringing, or someone shouting ‘mum!’ was like chisel on stone. Ours is a sociable house, with people coming and going all the time, and it was torture.

“Looking back, it’s like staring into a black hole.”

She is clear about the source of her depression.

“It was hormonal, no question,” she states. “It was the menopause. The doctors gave me anti-depressants for nine months but I knew that wasn’t what I needed. Even my daughter knew – she said to me one day, ‘mum, my friends and I have been talking, and all of our mothers cried for a year when they were your age. You need to get HRT.’”

FitzGerald shakes her head. “They gave me an estrogen pill and within two hours, the difference was incredible. After 18 months, it was a revelation.”

She adds, earnestly: “And I think it’s great that young women are open about it. They are talking to each other about menopause, so hopefully when they get to my age they will recognise the triggers for anxiety and depression.”

Next up for FitzGerald is a seven-way auction for the rights to film her next book Worst Case Scenario, set inside the criminal justice system – “it will be Americanised, which is a shame for Paisley,” she smiles – and she has been commissioned to write the TV script for her novel Australia Day, which has been described as ‘domestic disaster noir’ in its exploration of small-town secrets set against a devastating bush fire.

“Natural disasters interest me, they seem to be happening more and more,” she says. “I’m loving writing it.”

She admits to a dose of ‘empty nest syndrome’.

“Anna is already at St Andrew’s University, and Joe is about to go too,” she says. “Anna is studying international relations, and Joe is studying computer science.”

She applauds: “They both like writing but hooray, they will get sensible jobs.

“We had a lovely summer, everyone at home. Serge and I spent a lot of time hanging around the house like bad smells, following our children wherever they went.”

She admits to having ‘gone off’ Australia. “For 18 years on the trot, we would travel to Australia in the winter and Italy in the summer, and I wanted to do something different,” she shrugs.

“I didn’t make it to Australia for the filming, because I was unwell. But my mum was there, telling everyone who would listen it was her daughter who had written it, and I saw a photo of my brother-in-law holding a camera, so they all got involved.”

She adds, in awe: “It really is fantastic, seeing what the team have done with the story. It’s what I’ve been waiting for.”

Before we leave, Helen suggests the nearby Necropolis as a backdrop for photographs to go along with the article.

“It fits in with the feel of the show,” she explains. “It is Gothic. It is pure horror.”

The Cry, tonight, BBC1, 9pm