"She was living with violence -- and she wanted to write a novel showing how easy it is to become trapped in that kind of relationship, and how difficult it is to get out.
"At her funeral, I told myself I would write the story for her."
But For The Grace is set in 1990s New Zealand, and tells the story of feisty lesbian couple Leah and Kelly, who run a group for battered women at a local community house.
In the background, the Department of Social Welfare is reluctant to fund social workers without university qualifications -- and so sends the "academic and introverted" Dr Mandy Brook to audit Leah's group.
As part of the audit, Mandy gets the women to write journals, in which they reveal their experiences of violence.
"I've been told it's a good read -- that it's an exploration of a public issue, but also a thriller and a mystery," Sutton said.
"Plus, the characters introduce some ideas on family violence policy which I hope will attract some attention."
When writing, Sutton drew on some of her experiences as a counsellor with various organisations, such as Relationships Aotearoa, Presbyterian Support, the former Department of Social Welfare and Wairarapa DHB, and as a teacher of counsellors and social workers.
"None of the characters are based on real people, but I've heard a lot of the stories in my work -- and they all have very similar themes.
"Violent relationships are complex -- they have an allure, as the men are often vulnerable because of their own pasts, and that's hard to walk out on.
"People's vulnerabilities can make them quite dangerous."
Sutton said writing the book was "a long labour", from which she took several breaks.
But she started again, as she felt "the characters nudging [her] back into it."
"The characters kind of took me over -- the more I thought about them, they more I had to get them on paper."
Gaye Sutton's book But For The Grace, published by Fraser Books, will be launched at Aratoi on Sunday September 27 at 2pm. She will also appear at a speaking event at Almo's Books on October 25, as part of the Kokomai Creative Festival.