Mel McGrath is no stranger to terrifying and tortuous plots – she has fabricated many.
But nothing prepared the self-confessed “Essex tough girl” for a bloody murder bid she and her partner witnessed from the window of their London home.
The Oxford University graduate reveals it was the terror of that daytime attack and the impact of intervening that spawned her newly-released psychological thriller The Guilty Party.
Focusing on friends who fail to help when they see a woman in trouble on a night out – a woman who later ends up dead – it explores the costs of doing nothing and the stories we tell ourselves to make our actions more palatable.
She says: “I wanted to talk about four friends who witnessed one of those assaults, who decide to walk away and the price that they pay in terms of not only their friendship and the bond between them, but also in terms of their souls.”
And Mel, who is best known for her Arctic Circle-set crime series featuring Inuit hunter and guide Edie Kiglatuk, relives the moment she witnessed the near slaughter of a helpless man.
Mel says: “Two guys attacked another young man with an axe, a machete and a weapon dog – the dog bit off the guy’s nose. Truly terrifying. You never get out of your head the scream of someone who is being attacked in that way.”
While Mel usually avoids painting violent scenes in her books, she admits her latest offering is the exception: “There is a description of an attack right at the beginning – and it’s really informed by witnessing that level of violence.
“The interesting thing, too, was that when my partner and I came to give our statements to police, we had completely different versions.
“That is something I also explore in the book. Those four friends have completely different versions of what happened.
“Each of them decides what happens in a way that gets them off the hook.”
Mel was among court witnesses in the attempted murder case of eight years ago. There was no conviction and she admits she feared reprisals.
She recalls: “The price of intervening is high.
“I remember we left our flat for a bit because the perpetrators were local.
“The book looks at all those things about people who are innocent, who happened to witness something random happening on the street.
“You witness an act of violence, in your neighbourhood or in your home, you never walk away from that, whether or not you intervene.”
And she whispers: “It’s quite dark.”
Mel McGrath The Guilty Party, HQ, £12.99