She has exposed corruption and child abuse, and has fearlessly investigated gangs specialising in human trafficking and in the harvesting of body tissue.
For her latest adventure, at the hands of her creator, Anna Smith - herself a former journalist - she is pitted against the thugs Ulster Volunteer Force and their activities in Glasgow.
Not for Rosie the easy life of a 9-to-5 deskbound journalist, then.
The book, Betrayed, has as its backdrop the religious divide between Catholics and Protestants in Northern Ireland and Scotland.
It also recalls allegations that cocaine was smuggled into Scotland aboard Rangers' supporters' buses during the team's 1999 Champions League campaign.
"It's a difficult subject to tackle," Anna admits of the UVF storyline, "and one you're either encouraged to write, or to stay away from.
"I wanted to write a story about the people behind this.
"I spent quite a lot of time in Belfast during The Troubles - you'd be sent over there if a major atrocity had taken place.
"I interviewed people from both sides - some people who had lost family members, and some of the hardmen too.
"Sometimes you'd go into the house of a man whose wife had been killed.
"He would be preaching all this dogma to you, but what always struck me while they were talking was that normal family stuff would be going on around him.
"There would be wee kids running around the house, wee kids who had lost their mum.
"There would be dishes stacked in the sink. It was just like a perfectly normal household.
"I was always struck by the normality of such people, and I wondered if it was possible to write a book about that, that sort of dogma and normality, and bring it into a more localised area.
"These guys always made me think that, when they were not doing what they did, they were just like the rest of us.
"What I've tried to do in Betrayed is to paint a picture of them - who their wives are, who their families are."
Another strand of the plot concerns a tip-off Anna once received during her own, distinguished, journalistic career, about cocaine allegedly being smuggled across Europe on buses booked by Rangers fans to follow their team in Europe.
"It wasn't the Rangers fans - they didn't know anything about it," she says.
"According to the allegation, certain buses leaving Glasgow and other places would have a couple of hardmen on them, carrying holdalls full of money, and they would come back home with holdalls full of cocaine.
"I tried to investigate this, but I didn't get too far on it.
"However, I also remembered a court case in Glasgow, years ago, concerning gangsters who would smuggle drugs on buses that ferried kids over to football tournaments on the Costa del Sol.
The book is full of a lot of well-informed stuff like that." Anna adds. "There's a lot of interesting material on the UVF, too."
The book opens at a Rangers fans' smokers' night, "which is really a UVF night - a lot of these events are more sectarian than they seem.
"There was a belief that some of the proceeds from Celtic supporters' smokers' nights went to the IRA - especially years ago, back in the 1980s and 1990s."
"It was exactly the same for the Rangers' smokers' nights, though with money going to causes on the other side of the divide.
"By the end of this prologue at the smokers' night, the reasons for the betrayal become clear.
"A lot of the book is about loyalties. It's about an organisation that is secretive, in which everything is based on loyalty. But it's also about relationships, about regret and love.'
Anna says people "on both sides of the divide" who have read the book have voiced their admiration for its strong characters.
She says she did not shy away from using, in Betrayed, valuable knowledge that she gained during her career as a journalist in the west of Scotland.
"I could have done it with a lot less of the graphic knowledge that I actually have, and made the book a bit more lightweight.
"But there is lots of authentic detail in there - for example meeting places and the various ranks within the terrorist organisation.
"If you are going to engage readers' attention, then you should make your detail as true-to-life as possible."
Rosie Gilmour's career as an investigative reporter has already won Anna lots of fans.
The stories have sold well in traditional book form, and also on Kindle.
Her adventures aren't over yet. Expect to see even more of her, soon.
n Betrayed is published by Quercus on May 8 and is available in bookshops (£7.99) and online. On the web: http://www.annasmithscotland.com