If you book a seat for Good With Faces you might only use the edge of it. This is a hugely assured psychological thriller, performed with just the right precision and edge. It is written and directed by Oisín Kearney, whose collaborations with Michael Patrick included the 2018 fringe hit My Left Nut, which transferred to TV – this could easily do the same.

I’d advise watching it without knowing anything else first. The two-hander opens with social worker Hegarty (Patrick McBrearty) training his video camera on newly single mother Garrick (Clodagh Mooney Duggan) in her hastily tidied living room, with children’s toys swept under the sofa. Garrick’s son has a bruise, which has led to this referral. It’s a matter of procedure, a discussion “for internal use”, Hegarty assures her, in an opening exchange where every comment sparks suspicion and even the correct pronunciation of bourbon biscuit is scrutinised.

As it transpires that Hegarty already knows the answers to the questions he is asking, Garrick begins to crack – but she swiftly turns the tables so he is left scrabbling for explanations. Offsetting Katie Richardson’s discordant sound design are pregnant pauses as seemingly casual comments and assumptions are left to curdle, or moments of dark comedy turn into terror.

Much as the choice of each word could send the drama spinning in a new direction, the slightest physical behaviour may lose each the upper hand. Hegarty jokingly (and inappropriately) suggests she trust-falls into his arms to help things along; she touches his leg – or is she just brushing away a crumb? – when he shows her family snaps on his phone, only to give away more than he’d like.

Never didactic, Kearney raises the pressures of parenting and care work in a considered examination of blurred professional and personal lives impacted by a harsh economic climate; it has something in common with You and Me (and Whoever Comes Next) at Summerhall. Using a web of motifs, he gives the most mundane images – a glass of milk, a few nail clippings – an unnerving meaning. A bold and engrossing hour of shifting sands with an awful lot to say about blame, shame and many shades of abuse.

• At Summerhall, Edinburgh, until 31 August

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