But far from enjoying the release, Hauxwell is preparing to get started on book four.

"I never expected to write a series. It was a big shock," she said.

"When I wrote the first one, I remember the publishers asking me where I saw it going.

"I told them I might do a trilogy but they were excited by a series and said it can take four or five books to (completely) build the character."

Hauxwell's latest book, A Morbid Habit, comes after the success of her first two books In Her Blood and A Bitter Taste.

It sees heroin-addicted investigator Catherine Berlin duck out of Christmas lunch with her mother to travel to Russia for a for a new job.

"(Catherine) is broke and offered a job in Moscow. When she arrives her passport is taken and her opium medication confiscated because methadone is illegal in Russia," Hauxwell said.

"So before she even gets started she has some problems and it just gets more and more complicated from there."

The Castlemaine author has combined a tremendous amount of research with life experiences to create Catherine Berlin.

"(Catherine) has done a lot for the mortgage and I've sort of become fond of her," Hauxwell said.

"She's not a character you warm to, it takes a while. She tries to stay on right side of the law and has a strong sense of justice. 

"She tries to to do right thing and that’s all you can ask for."

Hauxwell trained as a lawyer in England and works as an investigator. But she doesn't have anything to do with drugs, leaving that aspect of the stories to her imagination and research.

"I'm still investigating and head off for (a new) one (soon). I just have to remember which hat I'm wearing," she said.

"I'm doing much less work and more writing, which is good but I do miss investigating." 

She will also appear at Gisborne Library on July 31. Bookings are essential. Phone: 5428 3962.

A Morbid Habit by Annie Hauxwell out now.