When I picked up my ticket for Frozen the lovely girl on the box office made sure that I wasn’t expecting a sing-along tale of princesses in snow, anecdotally recalling that a mother had brought her two children the day before and had to leave – because this Frozen couldn’t be further from fairy tale. This Frozen tells of a criminal act so unfathomable that it leaves all in its wake frozen in time by its cruelty, and its perpetrator frozen in a cycle of abuse that began when he was a child. Bryony Lavery’s chilling 1998 play feels as current as ever, exploring the abduction, molestation and murder of a child from the perspective of the mother, the offender and a psychiatrist.

The subject is chilling all on its own – something we read and hear about far too frequently, but always absorb with the notion that it’ll never happen to us. Lavery presents us with three characters that all question that: a mother, Nancy (Sally Grey), like any other, and a paedophile, Ralph (Mark Rose), who appears on the surface to be like any guy walking down the street. The psychiatrist, Agnetha (Helen Schlesinger) is the most interesting of all; having studied the psychological patterns of serial killers and paedophiles for years on end she naturally and intelligently bombards us with information. Managing to show that she is just as vulnerably human as the rest of us, we see her cope with her own tragedy.

Written as a series of monologues, the angles of the plot appear over a period of twenty years. Mentioning no names, I was told once that the pitfall of a monologue is that there has to be a build-up – the audience has to really care about a character before we can focus on them, alone, speaking at us. Lavery and director Ian Brown blow this shaky (at best) opinion out of the water by drawing us in immediately and abruptly with no words at all. The opening minutes consist of Schlesinger having an emotional breakdown, recklessly wailing and sobbing until there is absolutely no doubt that we care.

Conversely, Grey’s Nancy isn’t a ‘woe is me’ mother who has lost her child; she fights and breaks, then fights and breaks again. This is kind of the buoy that keeps Frozen on the surface instead of drowning deeper into an indulgent, despair-ridden play. It is real and it is sharply moving. Nancy goes through so many natural reactions: unfounded hope, an inability to favour her remaining child, wallowing, rebellion and ultimately forgiveness. Grey does this with such normality that it is completely harrowing.

On the other end of the spectrum, Rose’s Ralph is far from normal and yet dangerously alluring, clutching at our sympathies. He talks and thinks in a beguiling rhythm that gave me the shudders. He invests Ralph with the odd combination of being intensely thoughtful and yet emotionless. He is captivatingly good, but at the same time I hated him.

If I had any criticism it would be of the staging. Though it is necessarily simple, the spacing and angles make it difficult for everything to be seen at one time, or to be seen at all, depending on where you were sat. Other than that, Frozen is deeply affecting and multifaceted. Just don’t expect to be skipping back down to Finsbury Park Station.

Frozen is playing at the Park Theatre until 11 April. For more information and tickets, see the Park Theatre website.