Visual arts: Reviewed - The Night Demesne Colin Martin, Ashford Gallery until Sept 28, 01-6617286, Three new works Niamh O'Malley, Green On Red Gallery until Oct 14, 01-6713414

The Night Demesne in Colin Martin's paintings, at the Ashford Gallery is apparently the garden and surroundings of a large house. "Apparently", because while the fragmentary views that make up the sequence of images may not in fact depict one site, the logic of the show suggests that we read them in that way. It is as if we are glimpsing disjointed scenes from a story that is never spelled out. This is a device that is widely used in contemporary art in one form or another, and at first glance it might seem wilfully perverse.

After all, why allude to a potential story if you never get around to telling it? Presumably because the story is not the point. Rather, the point lies in various kinds of narrative conventions and spaces themselves. It can be argued that our relative familiarity with these conventions allows us access to the paintings and gives us some imaginative leeway within them. Whether in textual, theatrical or cinematic form, we usually follow narratives in a linear, cumulative way, and our interest is more often than not sustained by a level of suspense. Citing the example of Scheherazade, Walter Benjamin alluded to this when he observed that the purpose of storytelling is to postpone the future.

If all questions are answered instantaneously within the framework of a given narrative, there can be no suspense. Which is the problem painters face when they venture into narrative territory. Paintings can and do reward sustained attention, revealing more and more aspects of themselves over time, but, narratively speaking, they are pretty much instantaneous, which is probably why narrative paintings traditionally focused on decisive moments or - another solution to the problem - hidden meanings.

Martin's work has from the first displayed a keen interest in narrative strategies but, as with many other contemporary artists, he eschews decisive moments in favour of more problematic, ambiguous images. Characteristically, there is a sense of things going on behind the representational surface we are offered. This was true of his paintings of childhood, which imparted a remarkably strong sense of brooding inner life, and sometimes a hint of underlying darkness.

The latter was strongly apparent in his subsequent landscape-based works, which were laced with unease.

Darkness, what is not seen, is at the heart of The Night Demesne. Martin has clearly worked on the problem of describing darkness in paint, and he has come up with a dense, inky black, brushed on thickly, so that it is overtly flat - we can see it's paint - while yet allowing the implication of depth. Furthermore, it's the kind of darkness that is generated by intense artificial light: an absolutely impenetrable curtain beyond the radius of the electric glow.

It's as though we are making our way around Martin's demesne by torchlight, directing the beam now on to a decorative pond fringed with flowers in pots, now on to an opened cardboard box, now on to a boat covered by a tarpaulin. There is the disorientation of seeing things out of hours, so to speak, in an almost voyeuristic way. Then there are the possibilities suggested by what we see. What was or is in that box, for example? Although the paintings' structure tends to cast us, the audience, in a role, the nature of the role is crucially ambiguous. The question that might be asked, at its most extreme, is whether we are predator or prey.

The paintings do fall down somewhat in terms of their level of delivery. Perhaps deliberately, they are framed and glazed as though they are photographs, and they are overtly photographic in manner, in terms of composition and optical effects. While technically Martin is a very good painter, and has a real pictorial instinct, what he is trying to do here demands a level of sheer verve and confidence that don't quite materialise. This isn't to say that there is anything much wrong with the paintings and, indeed, the show, more that they are almost, but not quite, excellent.

Niamh O'Malley, showing at the Green On Red Gallery, explores the overlaps and differences between still and moving images. There are three projected installations, designated as "vignettes", in her exhibition. Each is a video loop recording repeated, simple sequences. Pedestrians pass by and a Dart train crosses the bridge in Talbot St; swimmers jump into the water and climb out again in Lough Owel; walkers crest a ridge in Croagh Patrick, descent.

So far, so many moving images. But in each case substantial sections of the projected setting for the vignettes is painted on to the screen. The result is that the painted portions of the image have a more consolidated presence. When someone passes in front of the painted image, they might as well be a ghost. They suddenly seem immaterial. As each loop reaches its conclusion before starting again, there is a calculated pause so that we see just the fragmentary, painted image.

There is an implication of transience in all this, not just because the figures can suddenly seem insubstantial against fixed backgrounds, but also in the repetitious nature of their activity: life is routine, and then we fade away. Yet O'Malley's methodology is repetitious in ways that are limiting, as well. The same formula is applied over and over, and the same points are raised. But perhaps it's unfair to complain about a lack of momentum in what is a small body of work. There is a distinct, interesting tension between the character of still and moving images in her work that calls out for further investigation, and presumably she will go on to do it.