Is living in Uxbridge such bad news? The titular heroine of Simon Stephens’s compelling new play Harper Regan in the Cottesloe, prompting a magnificent performance from Lesley Sharp, is a character in crisis, out on the edge, poised in flight from her job, her husband and her daughter.

As in his last play, Motortown, which charted an episodic period of non-adjustment in the return to Britain of a serving soldier, Stephens writes the geography of a soul in torment, a spiritual odyssey as well as a physical one. Harper needs to go home to Stockport to visit her dying father. But she also needs to leave Uxbridge, the anonymity of her adopted home near the airport with views across the country towards Oxford.

The play is devised as a series of collisions through which Harper can learn to breathe a new life of self appreciation. The disturbing secret of her marriage may or may not have contributed to this process. A piece of falling masonry has narrowly missed its target, but the outer accidents of the real world signify only the necessity of coping with inner turmoil.

This quality of fateful, mysterious ambiguity and anxiety is superbly conveyed by Lesley Sharp, who has the rare knack of making you feel exactly what the character is thinking without spelling it out. She endures the trite waffle of her employer (Michael Mears) in a haulage company while dreaming of a world elsewhere.

On the banks of the Grand Union canal she encounters a beautiful young boy (Troy Glasgow). In a pub at eleven in the morning, an uncouth journalist (Jack Deam) praises her “attractive shoulders” and launches into an anti-Semitic rant before she takes decisive action: an act of violence is committed and she absconds with a leather jacket as a sort of token.

Scenes of domestic responsibility at the hospice where her father is dying and in her mother’s (Susan Brown) house which she has not visited for two years jostle against her sexual escapade with a married man (Brian Capron) in a posh Manchester hotel. Her father was a teacher. Her parents are separated. She walked out of her house and has just kept walking.

Marianne Elliott’s production, eerily designed by Hildegard Bechtler as a series of interlocking locations in an impersonal landscape, reaches a moment on transfiguration at a future point in Harper’s story, but there is no real resolution. You realise, in fact, that the play has been a story of expiation, and that Harper has gone through the mill just as much of telling what happened as of allowing those events to overtake her. And the sad, slow hum of Lesley Sharp’s performance is the best explanation of all.

-Michael Coveney