Melbourne writer Laura Elizabeth Woollett is talking about one of the worst men who ever lived, and also – because she can identify with her – the woman who became his lover. The man was Jim Jones, the cult leader who ordered 918 people to kill themselves in Jonestown, Guyana. The woman was Carolyn Layton, a California woman who became his enabler.

Woollett, 28, has based her second novel around the character of Layton. She has called her Evelyn – “sleek-haired and oppressively brilliant”. With her young husband, Larry (Woollett calls him Lenny), she was a central member of Jones’s Peoples Temple, which was founded in Indiana in the 1950s, peaked in California in the 1960s and imploded in the most sinister of ways in 1978 when those 918 devotees drank cyanide-laced punch.

Woollett and I could talk about cults forever. I co-wrote The Family, about Anne Hamilton-Byrne and her secretive white-collar cadre of child-stealing cult members from leafy Melbourne. Hamilton-Byrne is still alive at 97, in suburbia, still feted by the dwindling few who surround her. Dementia renders her nonsensical.

Jones died with his followers in South America, a gunshot wound to his head, the gun at his side. He was full of drugs and as paranoid as it is possible to be.

Jim Jones, founder of the Peoples Temple sect, in Jonestown in November 1978. Photograph: Greg Robinson

The Family is nonfiction; it’s all true. Woollett’s Beautiful Revolutionary is fiction but heavily based on fact. She calls it “historical fiction” and her research was as exhaustive as for a nonfiction project. She interviewed former cult members and tootled around Redwood Valley in northern California on a bike looking at locations that had significance between 1963 and 1970. She had help from Rebecca Moore, Layton’s sister, a retired professor of religious studies and Jonestown website administrator. Woollett went through archival material from the California Historical Society, including primary sources bequeathed by Layton’s family.

It was here she found the notebook.

“Small things you can find,” she says. “It was a little black book.” There was no name in it but she is sure it belonged to Layton. Most of it was not useful except for one scribble, which said: “Father, I don’t mind dying today, but if we have decided not to we better leave for work pretty soon.”

“Father” was what followers called Jones; he told them he was a reincarnation of Buddha, Jesus, Lenin and Gandhi. He offered a sort of evangelical, isolationist socialism. He was an aggressively bisexual drug user, liar and narcissistic psychopath. The scribble in the notebook revealed to Woollett plenty about how his lover felt about him.

“It was a weird insight into their personal dynamic,” Woolett says. “It definitely informed how I wrote about them. When I read it, I got a chill because I felt so strongly it was her. It was special, like catching something rare.”

When researching a book, some material falls from the sky. Other things you hunt. Putting together The Family, we “obtained” hours of audio tape of Hamilton-Byrne’s sermons. We couldn’t speak to her because of her dementia but here she was talking: contradictory, cruel, plagiarist and dishonest, but compelling and authoritative. Jones also left behind hours of tapes. It’s amazing to hear utterly demented people like this talking at the peak of their powers. Tone of voice, phrasing, it all matters. The gaps and pauses and mispronunciations.

Anne Hamilton-Byrne, the leader of Melbourne-based cult The Family. Photograph: Melbourne international film festival

“Jim sounds quite nice to listen to, actually,” Woollett says. “He keeps it interesting for hours and hours and hours.”

In his prime he looked like Elvis, with big hair dyed black and painted-on sideburns. Hamilton-Byrne was addicted to facelifts, drove Jaguars and Daimlers and wore wigs and expensive clothes. Both cult leaders were textbook narcissists with uncanny similarities, including dysfunctional childhoods and fear of the outside world. Ultimately, cults big or small, and cult leaders, can trade in one thing: belief.

“I think on some essential level it’s appealing for people to believe in something rather than nothing,” Woollett says. “It gives you a cause or a sense of meaning. You join something that already exists and it gives you a structure. It’s crucial to know Peoples Temple seemed like a really good thing in the beginning and I think, even at the end when it was horrible, there were still remnants of those good things. There was still that belief on some level. It’s a very human impulse to think things will get better.”

Woollett developed the novel slowly, through ideas in her 2016 collection of short stories, The Love of a Bad Man, shorter pieces online and even a TV script. She wrote her first novel, The Wood of Suicides, about a girl and a teacher, based on Greek myth, at just 24. Jones is a background character in Beautiful Revolutionary; an animalistic, charismatic presence, sometimes close to the visceral narrative, sometimes a menacing blur. The story is of the doomed coupling of Evelyn and Lenny (Carolyn and Larry).

“Here were two young people who joined the church at the same time and she rose to power and they both had roles in the final tragedy,” Woollett says. “It was all quite remarkable and horrible.”

Both were pacifists and humanitarians. Woollett can relate to both her protagonists. But she relates to Carolyn more, or at least understands her more.

“As soon as I read about Carolyn I wanted to know everything about her and write about her,” Woollett says. “I see her as someone who values certainty even if she doesn’t really like what she’s doing. I think she likes the idea of doing something well. I see ambition in her. The desire for certainty. It’s an appealing notion – to believe in something and be invested in something wholeheartedly. I think that gives her a sense of meaning.”

• Beautiful Revolutionary by Laura Elizabeth Woollett is out 30 July; The Family by Chris Johnston and Rosie Jones is out now. Both books are published by Scribe.