Why? Nikki had tapped into an unusual area of source material ... the afterlife.
Because Nikki is a psychic medium.
A former medical physicist at the Southern General Hospital, she now works as a Reiki therapist and is editor of the WitchHiker's Guide, a magazine covering "all things alternative in Scotland".
Nikki, who grew up in King's Park, began receiving messages from spirits as a teenager and, over the years, she's found her head bombarded with some incredible images.
"Some experiences were so trauma-inducing I felt the only way to cope was to write them down," explains Nikki. "The result is Dead Men Talking: The Beginning of the Black Light, which will be published later in the year."
What sort of experiences? Three years ago Nikki was appearing at a Glasgow hotel, hoping to connect people with loved ones who had passed on. However Pat Jones, an Irishman who'd emigrated to Glasgow in 1850, came through to her – and wouldn't go away.
Nikki received details of Pat's life, including how he was controlled by the Calton gang, who murdered his prostitute girlfriend and her daughter. All nonsense? Well, the 35-year-old carried out research into Pat and his girlfriend and her daughter – and the information she'd received matched with that found in the Census records.
Yes, sceptics could argue she's researched the material first and came up with a ghost to suit. But why bother? The mum-of-one, who's secretary of her local PTA, is not in the work for the money or she'd be packing out the Pavilion.
But Pat didn't just want to tell his own story. He also told Nikki about a group of women who were being held in Govan, the victims of human trafficking. And Nikki made sure the police were informed.
Meantime, the medium had other issues to contend with. Her own family line was also beset by tragedy.
"In the book I bring in the story of my great-grand-mother, who lived on the Black Isle, and there is some fairly heavy stuff in there."
That's an understatement –the Mackay family history is the stuff of horror films, involving murder, rape, children sold for drugs, insanity and betrayal.
"I started writing the book about my grandmother's story but I kept putting it away. Then I had the idea of incorporating Pat's stories and weaving them together."
It works. Nikki's book sees central character Catherine (based upon herself) journey into her past to discover the frightening reality, yet running parallel to her story is Pat's history and the modern-day gangster world.
The strong narrative would make a great movie.
"It's an odd feeling, bearing the soul, with so much of the truth in there," Nikki admits.
"It's all based on real events and real people, with just some of the names changed."
Nikki, who is mum to six-year-old Jasper, has written books on healing and understanding love and relationship patterns. She doesn't appear before live audiences these days.
"I prefer to work with individuals, trying to clear the way ahead by dealing with the past," she explains.
"The other problem is when you do appearances before audiences you can have someone come through, but you often have to stop and move on.
"At Oran Mor, for example, a woman had lost a little girl to leukaemia and this girl was coming through to me, but other people were drinking and talking; if it's not relevant to them they're not interested.
"Plus, you don't have control of who comes through."
And she adds, softly; "I suppose it's entertainment but I prefer to work with individuals."
Today Nikki is skype-ing with a company in London.
"Last week I dealt with a business being targeted by a malicious ex-partner," she says. Tomorrow she's doing a session with a lady in Australia. And she's off to Coll soon to help locate a missing person.
However Nikki is already planning her next book.
"I got a piece of jewellery from my soon-to-be ex-mother-in-law, whose father had sided with the Germans during the war," she says.
"But as soon as this cameo brooch came into the house I got messages – the Jewish woman who owned the brooch originally had killed herself in the bath before she could be taken.
"I plan to go to Poland to research the story. But already I'm gripped. I need to know more."
Can she cope with the weight of responsibility of receiving such messages?
"It's not always nice," she admits. "The spirits who speak tend to have passed over in tragic circumstances.
"And sometimes when I hear things I get scared, especially when I'm being told the same sort of things are going on today.
"But you have to balance that with helping people through their confusion.
"For example, I can speak to someone and get a sense of where, for example, their depression is coming from. Is it passed down from the male line? Is it connected to child loss? War crimes?"
"And the appearance of such incredible stories does make for great storylines in a book..."
n Dead Men Talking: The Beginning of the Black Light, John Hunt Publishing, will be released in October but can be pre-ordered on Amazon