Sometimes, frankly, I expect not to like a show, but it’s so good-natured it thwarts my plans and instead offers up an evening of great fun. Watching One For Sorrow was the same kind of experience, except that fun doesn’t enter into it. I can’t remember when I was last bested like this by a serious play.

On one level, Cordelia Lynn has created a standard nuclear-family-plus-sudden-arrival piece: Bill, Emma and their teenage daughters Imogen and Chloe (the very names place them firmly in the middlest of classes) play awkward host one night to John. The twist is that out on the streets of London there is civil unrest, somewhere in the background an event similar to the Moscow theatre hostage crisis of 2002, and Imogen has subscribed to “#opendoor” on social media, inviting anyone who needs shelter from the chaos to come to their house.

The world outside the family’s living room means that the space within with its slowly grey-bleeding walls becomes a pressure-cooker for all flavours of liberal-under-stress assumptions. The opening argument between well-meaning old-school trendies Bill and Emma, excessively rigorous politics student Imogen and a Chloe trying desperately to be woke establishes the range of types and perspectives which are all interrogated by... actually, by John doing nothing very much at all. He doesn’t even take off his coat or accept a drink. But somehow the family decide that he’s doing nothing in a suspicious way (apart from Imogen, who develops capital-R Romantic ideas about him).

Irfan Shamji as John (oh, didn’t I mention the character is British Asian? There surely couldn’t be a racist element to the responses, though...?) shows admirable discipline in James Macdonald’s production. Once or twice he asks a question or makes a remark that’s keenly calculated to raise our own suspicions, but in the end it doesn’t matter whether he’s a terrorist himself or not. What Lynn portrays is our endless inventiveness as regards Othering people, followed by an all-too-familiar narrow range of acting upon those conclusions. I simply couldn’t decide what I thought about the play, until I realised that I too had been caught in the web of suspicion. That’s when I knew how successful Lynn had been.

Written for the Financial Times.