If there's one thing that artists hate more than having to explain their work, it's being labelled with a bunch of other artists as belonging to a new "school". If the artists in question happen to belong to what has been light-heartedly dubbed The New Glasgow Spook School, then their extra-sensitive antennae start to twitch nervously. Despite obvious parallels in their work, the Glasgow-based artists in question, Heather Nevay, Peter Thomson and Helen Flockhart, have never exhibited together before now.

This Saturday, that situation is set to be remedied when Victoria Cassidy brings the work of all three under one roof at her Mansfield Park Gallery in Glasgow's west end. Spooky epithets aside, the trio's paintings are certainly full of questions; of unsettling images, lonely figures and heavy symbolism - "such stuff as dreams are made on", to quote Prospero in Shakespeare's The Tempest.

For Cassidy, who attended Glasgow School of Art in the 1980s, overlapping with all three artists, the exhibition will be a long-anticipated event.

"All of them have international reputations and their work is much sought-after by collectors," she says. "I have admired them all for a long time and my husband and I have several paintings of theirs at home.

"There is a thread running through the work, but each artist paints in a distinctive way. They are all figurative painters and all their figures possess a vulnerability. They are not interacting with one another. They are alone, even with other figures in the frame. We often find a doorway or a window showing the way to another place, a picture within a picture, a world within a world.

"I've noticed a commonality between the people who buy their work. They enjoy the detail and with all three there are enough threads to weave a tapestry."

Over a cup of tea in her eyrie-like flat in the west end of the city, Heather Nevay - a surprisingly chipper companion despite the darkness of her work - is at pains to points out that the work is "not to everyone's taste".

Nevay, who graduated in printed textiles from Glasgow School of Art in 1988, has matured into a painter of real depth and skill in the four years since she swapped acrylic paint for oils, the medium of her painting heroes from the Italian Renaissance era.

There is real luminosity to her highly-charged vignettes, which depict a frozen scene playing with the idea of children making sense of the world while always keeping themselves to the forefront of the action to the exclusion of all others.

"I have created a world inhabited by specific characters," explains Nevay, who is at pains to point out her own childhood was a happy one. "They are constantly acting out scenes and as long as I know in my head what's happening, I'm confident the painting works. I like the idea of taking something awkward and uncomfortable and making it beautiful because it's easier to come to as a viewer. If I made it all blood-spattered, then people would turn away."

Flockhart and Thomson met at GSA studying under James Robertson and Alexander Moffat, respectively. Six years ago, they held their only joint exhibition to date, in New York, where their work is avidly collected. "We don't really see the connection between our work, but we know it's there," explains Flockhart.

"My work doesn't really have a thread of narrative running through it, but I think if there is a common thread in all our work, it is the desire to disconcert. Speaking personally, I try not to be concerned about what the viewer is thinking about, but at the same time, I like it to look beautiful."

Flockhart's beautifully realised work shimmers with restless energy and, while it is not decorative in a superficial show home way, it exudes a rich Pre-Raphaelite glow of jewel-like colour.

Unusually, for this new exhibition, she has painted a portrait of her husband set against a richly textured repeated patterned background. "I'm hoping it doesn't sell," he laughs. "It's unlikely she'll paint another."

"Yes," she retorts, "we could cut out the eyes and hang it above the fireplace so your luminous eyes follow us all round the room "

For Thomson, whose masterfully painted work is peopled by disparate voyeurs, whether in crowds, in small groups or alone, the story is always to the fore.

He has said in the past that his work is about "the way our lives fluctuate between contentment and crisis" and certainly his parallel universe is occasionally comfortingly familiar, while on the other hand, troubling. In it, as in all the work on show, we are all reminded that, ultimately we are all looking in on life while passing through.

Helen Flockhart, Heather Nevay and Peter Thomson's show at the Mansfield Park Gallery, Glasgow, opens tomorrow.