Coleridge deemed the narrative structure of The Alchemist perfect. But, I wonder. A landowner quits plague-ridden London and his cunning servants pose as learned sages in order to defraud affluent locals. Ben Jonson’s plotting is certainly adroit. The action takes place in a single location within the span of an afternoon, and this concentration of forces may have appealed to Coleridge’s idea of classical purity. What Jonson’s narrative doesn’t explain is why so many dim-witted toffs are kicking around in a city abandoned by all but its poorest inhabitants.

His characters’ names crassly signal their roles: Surly, Dapper, Lovewit, Sir Epicure Mammon. The chief villains, Subtle and Face, are assisted by Doll Common, whose vocation is self-evident, and in the early scenes their cheesy swindles are achieved with so little effort that one’s sympathy shifts away from the crooks and towards their prey. Which is not ideal. Jonson’s gallery of wealthy twerps seems stale to the modern eye: uppity monks, Spanish dandies, calculating apothecaries, aspiring duellists, mute virgins being touted for marriage by greedy relatives. The central figure is a deluded millionaire who believes his rusting bric-a-brac can be transformed into gold.

This glimpse into the Jacobean underworld is interesting enough, as a documentary, but it’s supposed to be much more than interesting. It’s supposed to be comic genius. The mental effort, however, required to find the play entertaining has a distancing effect. Comedy writers hate asking viewers to analyse the show because ‘an audience that’s thinking isn’t laughing’. Matters improve in the second act with a couple of decent plot twists and revelations. And the predictable return of the landowner creates some entertaining shocks.

Polly Findlay’s production has a wonderful overture of 17th-century music, which includes sly quotes from movie soundtracks: The Sting, The Italian Job, the Bond theme. Mark Lockyer is a satisfyingly shifty Subtle, and Ken Nwosu captures Face’s suave energy well enough. A bit more straightforward silliness might help. Ian Redford’s Sir Epicure Mammon looks too distinguished and senatorial for the absurd voluptuary whose insane (but wonderful) flights of rhetoric should be matched by an egregious physicality. What this leaden script really needs is a world-class comic like Matt Lucas or James Corden to bring it to life.

Hampstead marks the 30th anniversary of the Big Bang with a play about banking. Beth Steel’s sprawling script follows a pack of swinish Americans as they collude with chortling Hispanic kleptocrats to trash the economies of Mexico, Chile and Argentina. Then they do the same to Brazil, then to Iran and finally Greece. This unwieldy structure is marred by Steel’s conviction that every banking employee is a sulphurous, vain, immoral, coke-snorting, philandering, sexist thug who spouts clichés as if they were original insights. Every utterance is a platitude; smile and dial, you can’t cheat an honest man, a bank is a body that lends money to people who don’t need it.

This is a thoroughly American play with transatlantic themes and its creators, one assumes, have half an eye on New York. But the director Anna Ledwich opens the action with two characters trampling on the Stars and Stripes (bye-bye, Broadway transfer). Her hectic production goads and harangues the audience with hissy-fit lighting and a firing-range soundtrack that brings each scene to a close with the same three noises: sizzle, crackle, bump. These flimsy distractions are a sure sign that Ledwich lacked confidence in the script.

Beth Steel is a newish playwright who seems curiously uninterested in female characters. She has yet to learn that family scenes help to vary a play’s tone and to enrich its emotional texture. And though she’s adept at writing two masculine voices (bullying loudmouth, bemused novice), she can’t advance beyond these stereotypes and create a recognisable male creature with unpredictable emotions or an inner life. After watching her nasty clots spend three hours yelling soundbites from Economics For Dummies at each other, I was ready to drop.

And then, as if by magic, an epiphany. A needy banker asked a prospective date why she had spurned his advances. ‘Because you’re a cunt.’ Several in the audience whooped and cheered at this, and their bitter jubilation revealed to me a half-hidden truth about the subtle vigour of the free market. It can incubate wannabe Lenins who imagine that they threaten the system while remaining quietly restricted by its elastic and invisible fetters. A timid anarchist who lacks the guts to say ‘cunt’ to a banker’s face can outsource the job to actors in a play. And the play, a speculative effort facilitated by loans secured against box-office takings, reinforces the system by gratifying everybody concerned. The cowardly hothead gets to throw insults at the financier. And he banks the profits and prepares to reinvest in another make-believe assault on the market which will strengthen it further. Genius.