Neil LaBute’s Reasons To Be Happy is the second play in a trilogy that began in 2008 with Reasons To Be Pretty, and will conclude in the near future with the sublimely titled Reasons To Be Pretty Happy. LaBute claims that Reasons To Be Happy works as a stand-alone piece, and that the audience does not need to have seen Reasons To Be Pretty to appreciate it – which is good, because I haven’t – and to some extent, he is right. If one can look past the slightly implausible foundations of the play, presumably elucidated by its prequel, then Reasons To Be Happy becomes a richly allegorical, superlatively authentic almost-comedy that packs a surprisingly powerful punch.

Meet Greg (Tom Burke), a bookish substitute teacher in early middle-age, yearning for a better, more culturally refined life. Meet Steph (Lauren O’Neil), Greg’s fiery ex-girlfriend, with whom he still shares one of those fabled ‘special connections’. Meet Carly (Robyn Addison), Greg’s sweet-ish current girlfriend, Steph’s best friend, and a working single mother. And meet Kent (Warren Brown), Carly’s ex-husband, father to her daughter and Greg’s somewhat unlikely pal.

Like an episode of How I Met Your Mother – a delightfully curse-filled one – Reasons To Be Happy traces the fall-out from a surprise meeting between Greg and Steph in a grocery store parking lot. Friendships and relationships are shattered and re-forged, futures are demolished and rebuilt, lives – including an embryonic one – hang in the balance. It’s all very dramatic. It’s all supremely watchable.

LaBute’s writing is typically authentic, stuffed full of “sortas”, “likes” and “okaaaays”. To a generation attuned to it, it is nothing short of engrossing to hear the real, unadulterated drivel of twenty-first century American-English plonked on stage. Labute’s ability to forge a story – and a compelling one too – out of this language is a real indication of the quality of both his ear and his pen. Michael Attenborough – who has an established relationship with LaBute from his days at the helm of the Almeida – directs with complementary understatement, and Soutra Gilmour’s revolving magic-box set is equally classy.

The four-strong cast are thoroughly convincing. I suspect the sensibilities and sensitivities of individual audience members dictates which character they relate to most: the awkward, indecisive, non-confrontational Greg; the impatient, frustrated Steph; the resigned, cynical Carly; or the aggressive, no-nonsense Kent. LaBute has crafted characters and relationships that feel thoroughly three-dimensional, and Burke, O’Neil, Addison and Brown inhabit their roles entirely. In fact, we aren’t watching them at all. We are watching Greg, Steph, Carly and Kent.

Reasons To Be Happy is a slow-burner. At first, in spite of (or perhaps because of) his constant naturalism, it is unclear exactly what LaBute is getting at, if he is getting at anything. In the second half, however, he elegantly and organically makes his true subjects known: gender stereotypes, the all-pervading power of love and, above all, the sacrifices demanded by social mobility and the desire to improve oneself. Nowhere is this last more piercingly present than in his deafeningly quiet conclusion.

Masked in a veneer of contemporary vernacular and unrelenting naturalism it may be, but Labute’s play is as absorbing a study of human social patterns as anything from Ibsen or Chekhov. The Old Vic’s recent production of The Master Builder may have been an entirely different kettle of fish – although it explored similar themes – but Reasons To Be Happy is no less powerful, no less enthralling, and a damn sight more accessible for young audiences.

Reasons To Be Happy is playing at the Hampstead Theatre until 23 April. For more information and tickets, see the Hampstead Theatre website.  Photo: Manuel Harlan