The Motherf**ker with the Hat (National Theatre, Lyttelton)

Let’s talk, momentarily, about the Motherf**ker with the False Teeth. The old fella next to me spent 105 minutes – no f**king interval – clack-clack-clacking away like a newborn going hell for leather on his mother’s teat. It sounded like the sea slapping against rocks, like a never-ending Werther’s Original. I very nearly grabbed the motherf**cker with the false teeth’s false teeth and hurled them onto the stage.

Lucky for both of us, Stephen Adly Guirgis’s comedy is about patience, forbearance and self-control. It recognises that morality never takes time off, even for a second, and that years of good behaviour, hard work, abstinence or fidelity can be destroyed in an instant. Trust, like teeth, is slow to grow and quickly lost.

First seen in New York in 2011, with Chris Rock making his Broadway debut, it centres on Jackie (Ricardo Chavira), an ex-alcoholic and drug dealer fresh out of prison, ready to get both himself and his income stream clean. His girlfriend Veronica still uses and boozes – much to the concern of his shaggy-faced, sponsor Ralph (Alec Newman), a Hell’s Kitchen resident who swapped substances for smoothies.

Jackie’s resolve is tested, however, when he finds another man’s hat in Veronica’s cramped Times Square studio.

That triggers a New York run-around: down to a behatted (and, presumably, bemused) neighbour’s flat, armed with a gun; over to Ralph’s brownstone, where he wards off his sponsor’s frustrated wife (Nathalie Armin); and across to his ever-loyal Cousin Julio’s pad for moral guidance and support (Julio tends to pot plants. Jackie and Ralph both buy bouquets).

Through it all, Jackie spends the play teetering on the brink of drink and self-destruction with his parole hanging perilously in the balance.

Adly Guirgis writes with a peppery comic flair: all plosive apoplexy and somersaulting swearwords. But beneath that, there’s a careful moral compass and, in Indhu Rubasingham‘s fine-tuned production, it’s eloquently drawn out by Robert Jones’s top-drawer design. Locations glide in, flats fitting together as their walls fly down. They sit like islands on an empty black stage, as if only the here and now matters. Three fire escapes swivel above: reminders of the 12-Step Programme and of the ladder to success or stability.

We’re asked, very subtly, to judge Ralph and Jackie for the same indiscretions, despite their different circumstances: one’s a hippyish drop-out married to an ex-Wall Street broker; the other’s a Puerto Rican immigrant from a beat-up crime-filled neighbourhood. Neither’s absolved, but context is everything. Ralph and Jackie are climbing the same ladder. They just start on different rungs.

It’s never hectoring, though, and Adly Guirgis entertains first and foremost. His excellent (and largely authentic) cast have plenty to play with. Chavira is unshowily excellent, withholding all judgement on Jackie. Cuckolded in scene one, he has our sympathy from the start, then proceeds, bit by bit, to test it. Newman and his nutribullet make an obsequious pair, and he hides his superiority behind a reverent smile, while Flor De Liz Perez is both fiery and likeable as Veronica.

Best of all, Yul Vázquez makes all Julio’s absurdities – he preaches V for Van Damme-style vengeance – into a credible person and the play’s calm, collected moral core. The gent with the dentures has him to thank.

The Motherf**ker with the Hat runs at the National Theatre Lyttelton until 20 August 2015.