The irony of trudging through the snow-lined streets of London to watch a play called ‘Frozen’ was not lost upon us; nor was the fact that we very nearly didn’t make it to the Theatre Royal Haymarket due to a combination of ice-damaged trains and mainline stations closed because of snowdrifts.

Make it there we did, however, and before I go any further I should probably explain that this is not a post about ‘Frozen’ the musical, that of “Let It Go” fame. In fact, this 20-year-old play, written by Bryony Lavery and directed by Jonathan Munby, could not be further removed from the world of Elsa, Olaf and Anna.

Its focus is a grieving mother, Nancy, whose daughter disappeared years ago, but whom she still believes to be alive. Hope, however, is a cruel mistress: just a couple of scenes into the play we learn that Rhona is dead, having been abducted and killed by a paedophile who has killed a number of other children. The remainder of the play focuses on events leading up to an encounter between this man, Ralph (played by Jason Watkins) and Nancy (played by Suranne Jones).

It also examines the efforts of an American criminal psychology lecturer, Agnetha (played by Nina Sosanya) to understand what drives beings such as Ralph. Are they born evil? Are they victims of circumstances? How fine a line, exactly, divides paedophiles and murderers from the rest of us?

Cleverly, the first act of the play introduces us to each character separately. So it is that we see Nancy preserving her daughter’s bedroom as it was on the day she disappeared, convinced that she would “know” had anything bad happened to Rhona. So it is, too, that with Nancy we learn the awful truth about her daughter’s disappearance and grieve with her for the future Rhona is denied.

In the meantime, we come to understand that, glamorous and successful Agnetha might be, but every day she does battle with her own, haunting demons. None as haunting as the character of Ralph, though. It’s impossible to tear your eyes away from Jason Watkins as he alternately leers at, cajoles and – most frighteningly – reasons with his jailers and with Agnetha.

The first act sets the scene well and keeping the characters separate works for a finite period, but it’s fair to say that the play moves up a gear in the second act, as its protagonists are brought together. And here’s where things get really interesting, because ‘Frozen’ forces you to confront your own preconceptions. Calmly and meticulously, Agnetha unravels Ralph’s childhood and the horrific abuse he suffered at the hands of his parents. Repulsive as he is – and the play never loses sight of the horrific crimes he’s committed nor his apparent lack of remorse – it’s impossible not to feel a twinge of sympathy for Ralph or to wonder what might (not) have been, had his start to life been less cruel.

It’s the meeting between Ralph and Nancy that the audience is most keenly anticipating, though – and when it does happen you can hear a pin drop. I won’t give too much away; suffice to say that the dialogue and staging is spot-on and that Jason Watkins and Suranne Jones sustain the tension brilliantly as, in turns, they are drawn in and repelled by each other.

Despite its sombre subject matter, I enjoyed ‘Frozen’ very much. For the acting, certainly – I doubt I’ll see another performance as compelling as Jason Watkins’ this side of Christmas – but also for its delicate exploration of the human psyche. ‘Frozen’ doesn’t pretend to the have the answers to the troubling questions it poses. Instead, it brings us a world which might be cruel and is frequently bewildering – but one which does, ultimately offer us those three elements so crucial to the human spirit: hope, forgiveness and, above all, love.