Peter and Debbie are enjoying a cruise – a celebration of twenty years of marriage, and a break from their annoying teenagers. They befriend fellow passenger, Elsa Jean Krakowski, an eccentric American with a fondness for Donald Trump. There's something slightly unsettling in her overeager friendliness... but there's no point rocking the boat if you're about to get off it.

Back home, in the comfort of suburbia, Elsa suddenly turns up on Peter and Debbie's doorstep, unexpectedly. And when they look up their house guest online, unearthing some hair-raising evidence, their good nature is challenged as never before. What kind of danger have they allowed to take up residence in their guest room? And can they bring themselves to say anything about it? Sometimes, the truth is just too impolite.

Steven Moffat's play The Unfriend takes a hilarious and satirical look at middle-class England's disastrous instinct always to appear nice.