Currently writing her fourth thriller, ex-parole officer and social worker turned screenwriter Helen FitzGerald was in perpetual ‘movie development hell’, until her latest rejection prompted her to transform the story into a debut novel. ‘Dead Lovely came so easily,’ the Glaswegian-based Australian recalls. ‘It was like I’d been swimming upstream for years and suddenly turned around.’

A bleakly humorous account of accidental mother Krissie, who cheats with her best friend’s husband and admits to murdering her on the West Highland Way, it’s explicit from the first paragraph. ‘I don’t hold back,’ she says. ‘I like squeamish, icky bits. Working in Barlinnie, I’d see seven offenders a day. Glaswegians are great storytellers but they often had awful tales and it’s certainly informed my writing.’

One especially gruesome scene came from her husband, American Cousins scribe Sergio Casci. ‘He suggested the tent pegs in the eyeballs. And having read the book, I don’t think he’s any more scared of me than he was. I think he was always pretty scared.’

Her second novel, The Devil’s Staircase, due out in February, recalls FitzGerald’s experience of London squatting, while the follow-up to Dead Lovely will be My Last Confession (out next summer) which is already attracting BBC interest. Set two years on, the book is about Krissie getting too close to a prisoner. As a reformed wild child, 41-year-old mother-of-two FitzGerald concedes that there are a lot of things about Krissie that are similar to her. ‘But I’ve never killed anyone,’ she says. ‘I’m not as daft as she is.’

13 Aug (with Claudia Schreiber), 7.30pm, £6 (£4).