The Unfriend, Criterion Theatre review ★★★★★

This playwriting debut from Sherlock and Doctor Who writer-producer Steven Moffat, directed by his Sherlock collaborator Mark Gatiss, has a thrilling premise: Peter and Debbie, a middle-class, Guardian-reading couple from London meet the eccentric, glamorous and Trump-tooting Elsa from Denver, US, while on a cruise holiday. Their sunlounger chat is perfunctory enough for them to put their politics to one side, but when a casual promise to stay in touch leads to Elsa inviting herself to visit, the couple Google their accidental friend only to find she’s suspected of murdering six people – including her own family. Too awkwardly polite and British to stand Elsa down, Peter and Debbie end up hosting the could-be murderer in their family home.

The Unfriend has arrived on the West End trailed by largely positive reviews from its premiere at Chichester Festival Theatre last year. It’s easy to see why, at first; its pacy script rattles along on a laugh-a-minute formula, but then comes a plodding second half during which Moffat gets side-tracked by a tedious toilet joke that bursts the thriller’s tension and drags the whole thing down.

Frances Barber as Elsa, Amanda Abbington as Debbie, Reece Shearsmith as Peter. Photo: Manuel Harlan

The play runs like an extended episode of a TV sitcom, and bar the opening scene set on the deck of a cruise ship against the static backdrop of an ocean (note to the technical team to be wary of pieces of equipment like watches and laptops reflecting onto the screen and shattering any illusion), it looks like one too. The Unfriend is set in the couple’s fully fleshed-out kitchen and living room, in which designer Robert Jones has added all the finer details, from framed photographs to diffuser sticks and a roll of kitchen paper lurking almost out of eyeshot by the sink.

A trio of familiar faces do their bit to make it shine. We have Reece Shearsmith (Inside No. 9, The League of Gentlemen) as uptight scatterbrain Peter, hamming up the humour and landing moments of pure slapstick towards the end. Sherlock’s Amanda Abbington is the yin to his yang as light-hearted, eye-rolling wife Debbie. Olivier nominee Frances Barber is the show’s firecracker and on-stage puppet master as Elsa, wafting into the house with a trail of Gucci suitcases and unnerving its residents by spouting anti-vax comments in her scratchy drawl.

Amanda Abbington as Debbie, Reece Shearsmith as Peter, Maddie Holliday as Rosie, Frances Barber as Elsa, Gabriel Howell as Alex. Photo: Manuel Harlan

Supporting them are Gabriel Howell and Maddie Holliday, both strong as the couple’s teen children despite their two-dimensional roles; Michael Simkins as the passive aggressive, busybody neighbour we all love to hate; and Marcus Onilude, bringing impeccable comic timing to the role of PC Junkin, who should have been introduced sooner.

In a glorious twist, we see Elsa play a bad-ass Mary Poppins to the family’s fractured dynamic, while Peter and Debbie continue to fret over whether she’s about to bump one of them off. Then comes a final twist, which we won’t spoil.

Moffat’s thriller sitcom, an extended imagining of ‘what ifs’ based on the true story of his friend, has the premise and talent to have us anxiously laughing while our sweaty palms cling to the edge of our seats. It’s a shame it deviates to silliness and ultimately loses its way.