It’s an under acknowledged risk, being friendly. You never know what kind of person you’re inviting in with acts of careless kindness; how they will be interpreted, responded to, or all-out exploited. The Brits are, as a culture, more imperilled than most – they’d rather die than make a fuss.

Inspired by a real-life encounter of close friends, Steven Moffat (known for his work on Dr Who) literalises and lampoons this stereotype in his debut 2022 play The Unfriend, a comedy of manners offering up for the slaughter an English couple’s strangled politeness against another zeitgeist-flavoured type: American shamelessness.

Alex Lee, Tim Walter and Helen Thomson in Sydney Theatre Company’s The Unfriend. Photo © Prudence Upton

The latter arrives in the Jennifer Coolidge-like guise of Elsa, a gregarious “people-positive” extrovert (an appropriately scene-stealing, larger-than-life Helen Thomson) that Peter and Debbie (Tim Walter and Alex Lee) meet on a cruise. Elsa finagles their contact details and, unlike any normal person, actually follows up. Suddenly, a few days earlier than expected, she’s on their West Sussex doorstep with four suitcases, making brazen good of their disingenuous offer to “come visit”.

As if that wasn’t horrifying enough, the couple discover through last-minute googling a salient fact: this leopard-printed stranger happens to be wanted for murder. A segment from a ‘gotcha!’ TV show splatters the lurid details (and frumpy mugshot) across the second storey of their home, where two oblivious teenagers are sequestered.

Ty Arnott, Helen Thomson and Alex Lee in Sydney Theatre Company’s The Unfriend. Photo © Prudence Upton

Make that six murders, actually, including Elsa’s father, sister and late husband. Or, to quote one of Peter’s exquisitely cowardly euphemisms: ‘incidents of end-of-life care that you were involved in… proactively’. Already pushovers, the parents’ predicament becomes twofold when Elsa turns out to be “Murder Poppins” for their two surly kids, who are miraculously transformed by this American’s culturally exotic unapologetics.

Alex (Ty Arnott, who embodies teenage angst with comically boneless dramatics, flopping and moaning) is schooled to state plainly his reason for exiting the living room rather than strategically farting, for instance. Over-anxious Rosie (Brooklyn Davies) also benefits from Elsa’s ironically life-affirming instruction.

Tim EWalter and Helen Thomson in Sydney Theatre Company’s The Unfriend. Photo © Prudence Upton

With puckish direction by Simon Phillips, the comic discomfort of The Unfriend springs from the two party’s very different ways of addressing reality, and the devolution into madness that ensues. Elsa’s is a flagrant and unapologetic bulldozing into and through the truth. Her lies are through omission, minimisation of ‘facts’ over ‘personal truths’, and outright fibs. (Sound familiar?)

Peter and Debbie are themselves compulsive liars; their polite breeding demands it. Pathetically, and with dizzying linguistic exertions, they mince their language to evade, equivocate and – most importantly – appease. When his daughter says he should be more like Elsa, Peter replies: “That would be… controversial”.

Huw Higgginson in Sydney Theatre Company’s The Unfriend. Photo © Prudence Upton

This dissonance simultaneously plays out in the play’s main subplot, which involves a neighbour’s dispute over a garden wall. Huw Higginson, in garden gnome bearing, whose thick country accent foils the family’s posh one, is hilarious as a chortling, passive-aggressive bore, prone to long and gormless periods of glazed inactivity. “Yer a busy man!” he laughs when, for the hundredth time, Peter fobs him off.

The set piece of self-sabotaging avoidance arrives later, subjecting a shrieking audience to a scene involving a sandwich plate, a police officer (Ben Wood) and an effluence-smeared toilet brush. The irony of this horrifying spectacle evokes the bon mot-meme: “Oh, you’re a people-pleaser? Name one person that’s pleased with you.”

As things escalate, Walter brings some forehead-first physical comedy to his character’s flailing derangement, folding over to press his head into cushions, against the wall, the open fridge, and so on.

The farce of it all rubs itself happily against Isabel Hudson’s set, a wonder of verisimilitude. After the cruise ship deck vanishes upwards in the opening scene, we spend the rest of our two-act time in the family’s home, which is tasteful and well-furnished, with warm autumnal tones.

Light spills through sheer curtains in a half-hidden room at the back; when the front door is opened, an optical illusion creates the impression of a street outside. The upper storeys shuttle about ominously at one plot crisis point, but the effect in its isolation feels a bit ‘gothic gimmick’. Otherwise, this gorgeous design is a serene counterpoint for social chaos.

There’s something inoffensively facile about The Unfriend; showing off Moffat’s wordplay, it works in very broad, silly, then scatological strokes. Fundamentally ambivalent, progressively mortifying, The Unfriend nonetheless holds up a winking funhouse mirror to our divided, truth-troubled times.

The Unfriend plays at The Rosyln Packer Theatre, Sydney until 31 October.