THERE is something about a conman, at least when he’s exploiting and exposing greed and folly, that is perversely attractive — or so Ben Jonson, that mix of moralist and monster, suggested in The Alchemist.

And when Simon Russell-Beale and Alex Jennings scramble from disguise to disguise and expedient to expedient as they maniacally cope with a deluge of undeserving victims — well, one is inclined to agree.

We meet them — Russell Beale’s snarky, cockney Face in a grubby vest, Jennings’ disdainful Subtle in a dressing gown — slurping breakfast cereal while exchanging robust Jacobean insults.

Nicholas Hytner’s revival is, you see, updated to contemporary London yet faithful in spirit to Jonson. As if to prove the point, Ian Richardson’s Sir Epicure Mammon glides into the house they’ve commandeered: a Mayfair voluptuary in a silvery silk suit who dreamily gourmandises on the prospect of the gold mountains and gold lakes that Face and Subtle’s alchemy will bring him.

Others join him: Bryan Dick as a dim clerk who believes himself to be the nephew and heir of the Fairy Queen; Sam Spruell as a nerdishly oleaginous Anabaptist willing to be convinced that forging currency is lawful; and Amit Shah as the most harmless and topical of victims, an Asian tobacconist prepared to pay for prophecies that his shop “at corner of a street” will succeed. And each appearance gives Russell Beale and Jennings the chance to prove not only that they are slick collaborators in crime but that there is no funnier or more adroit double-act on the London stage.

In a series of twinklings Jennings is a beaded Californian guru manipulating dupes in a singsong bleat, then a grave Indian mystic in virginal white, then a crabby, rumpled Presbyterian. Likewise with Russell Beale, who one moment sticks on a toupée, beard and blazer to become a vaguely nautical blimp, and the next half-limps, half-scuttles onstage from the alchemist’s forge in protective glasses and a heavy apron, looking and sounding like a troglodyte arrived with accent from The Lord of the Rings.

Could our devilish duo and their helpmate, Lesley Manville’s cheerfully slatternly Dol Common, bring a bit more hardness and danger to their manipulations? After all, there is a point after which even morally instructive criminals aren’t so funny.

For a moment you think so. But then Richardson’s Mammon goes into voracious reverie: “I will have all my beds blown up, not stuffed: down is too hard.” Or Jennings’s Subtle promises a magic medicine that will cure “a great man of state” of the gout, flashing a photo of John Prescott as he does so. And, whatever its ethics, the evening is irresistible.

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