David Harrower’s acclaimed 2005 play, Blackbird, is the sort of work that always gets labelled “thought-provoking”. And so it is, but equally it is a compelling narrative full of the tension of uncertainty. Ray is in his mid-50s, apparently respectably settled and employed, but 15 years previously he was sent to prison for a liaison with a 12-year-old girl, Una. Though he has changed his identity, she now finds him and confronts him. The 75 minutes of their meeting (played without an interval) throws up equal possibilities of violence, transforming revelations and reconciliation, but rejects any glib solution. Perhaps the resulting ambiguity is one reason why the ending is Harrower’s only false step. Following a splendid coup de theatre in the closing minutes, the play ends in convenience, not conviction, but the unsatisfactory ending doesn’t diminish the power and intensity of what went before.

After his initial blustering attempts to get rid of Una, Ray’s initial concern is to convince her (and himself?) that he is not a paedophile, one of those men who grooms young girls for sex. Is he telling truth? I don’t know – does David Harrower? Ray claims that Una’s unhappiness is what brought them together. At 27 she still has a capacity for self-willed unhappiness, just as he is surprisingly judgemental of others. Most telling is the fact that in the two extended monologues that emerge from the realistically fragmented dialogue the real crime is seen as disloyalty to the partner: Ray finds himself defending himself against charges not of sexual abuse of a minor, but of deserting said minor.

Pilot Theatre’s production in association with the Theatre Royal is sure-footed, powerful, controlled and wonderfully claustrophobic. Director Katie Posner has the courage to allow stillness, especially in Una’s great monologue. Lydia Denno’s set is a triumph. Not only does it qualify as the most randomly littered set I’ve ever seen, but it manages to suggest that what we are seeing is actually the real room. Charlie Covell and George Costigan negotiate the fragmentary dialogue with remarkable naturalness. Covell’s Una moves from contemptuously aggressive agenda-setting, armour-plated with her own unhappiness, to agonised recall, to a No Man’s Land where solutions won’t present themselves. As Ray, Costigan shows the layers of self-justification peeling away strip by strip, but is the man we see at the end essentially any more guilty than at the beginning? Ray is clearly a flawed individual, but what exactly are those flaws?

Everything about the text, production and performances rejects sensationalism, embraces honesty and – inevitably, I suppose – provokes thought.