Frozen, Library Theatre, Manchester

The most chilling moment – and there are many in Bryony Lavery's eloquent play Frozen – comes when the convicted paedophile and serial killer is asked if he feels no remorse at what he's done. "What's that?" he replies blankly. Then, when trying to absorb the meaning of the word regret, he says: "The only thing I'm sorry about is that it's not legal... killing girls."

Lavery's exploration of the darkest side of life, the abduction and murder of a child, is by no means as depressing as it sounds. Roger Haines's effectively simple staging may lack the star names of the National Theatre production of a few years back, but Lavery's three characters are portrayed here with a nuanced insight that results in a riveting evening.

Each one is introduced with a monologue and the drama unfolds with soliloquies, interviews, and speeches. Playing a kind of three-part counterpoint, whose threads often cross, tugging at this difficult subject from different angles, the characters keep their intense emotions mostly under wraps, their inner feelings betrayed only by involuntary outbursts or abrupt gestures.

Agnetha, a criminal psychologist who travels with some heavy but unspecified emotional baggage, is in Britain to deliver a paper, "Serial Killing: A Forgivable Act?". Her research involves a series of encounters with Ralph, a tattooed misfit whose disturbing attitude and fatal violence towards little girls may be attributable to a brain disorder triggered by a childhood of abuse. The third in this bold three-hander is Nancy, the mother of 10-year-old Rhona, who was one of Ralph's victims 20 years ago.

As Agnetha with the Icelandic origins, Mia Soteriou humanises the role of the rational science lecturer with a touching sincerity, even though the revelation of her own unhappy secret produces perhaps one frozen heart too many in Lavery's otherwise well-crafted, unsentimentalised and sadly topical drama.

In a kind of flashback we are introduced to Nancy working in her suburban garden as she describes an afternoon in the humdrum life of her family. Her youngest, Rhona, has just run round to Granny's with the secateurs she needs to prune her clematis. It's the very ordinariness of it all that makes the bleakness so much worse as you realise that Rhona's own budding growth has been savagely cut down by a chance encounter with Ralph.

As he describes his ordered life, his neatly labelled collection of child porn videos, it becomes clear – his coolly distinctive speech pattern peppered with the word "obviously" – that for Ralph the systematic sexual assault and murder of young girls is a hobby.

Indeed, it's a pastime for which he's in constant rehearsal for the moment to pounce on his unsuspecting prey with a worryingly gentle "Hello!". John Killoran's performance feels chiselled out of stone and that is meant as a compliment. Terrifyingly normal on the surface, Killoran's Ralph – provocatively described by the psychologist as " sad, predictable, banal" – is locked into a petrified underworld from which there seems no escape.

By the time Rhona's tragic fate has been discovered, we've seen Nancy transformed into a campaigner and, by way of her descriptive accounts, we've got to know her surviving daughter and her (soon to be ex-) husband. Joanna Bacon makes Nancy vulnerable, numb, but also resilient, so that her eventual dialogue with the man who killed her daughter is not only searingly convincing; it's marked by her quiet, fearful certainty that she has been able to forgive him and move on.

Ralph's mental state is such, however, that we are fearful that he will uncomprehendingly brush aside her gesture of reconciliation. What happens next is so unexpected that it makes you question whether Lavery has perhaps just opted for a tidy ending. But that is not to detract from the heat of this compellingly acted Frozen amid the icy contours of a carefully considered production.

To 26 April (0161-236 7110)