Theresa Rebeck’s Seminar is a play that demands a big-name, big-talent lead. The original Broadway production chose Alan Rickman; the Hampstead Theatre have opted for the excellent Roger Allam, who commands the stage effortlessly throughout this immensely watchable but rather unextraordinary drama.

The set-up is this: four rich kids with literary ambition have paid $5000 each for the privilege of being instructed in writing by Allam’s aggressively cynical retired novelist, Leonard. They enter their first meeting full of ideas, optimism – and themselves – only to have their work ripped into and dismissed. Determined to impress Leonard, they all set about finding their own way to succeed, no matter how unethical.

There are lots of punchy gags and wince-inducing putdowns, and Rebeck keeps the piece short and sharp, but the whole thing starts to come apart at the seams under scrutiny. Despite there being only five characters, two aren’t developed past their archetypes (the clever, hot girl who uses sex to get what she wants and the pretentious, well-connected snob), and whilst Allam’s brilliantly horrible Leonard has a little more to him, it’s all rather predictable. Bryan Dick and Charity Wakefield, as Martin and Kate respectively, are given more to work with, and like the rest of the cast they really go for it. Wakefield in particular almost surpasses Allam with her neurotic, scene-stealing performance, but in the play’s final scene Rebeck quickly dispatches with Kate in favour of an over-long scene of male self-congratulation which is either very tongue-in-cheek or a bewildering tribute to the idea of Kerouac-esque genius.

Hampstead Theatre has essentially created a very good production of a very flawed play. The actors and director have mined an impressive amount from the underwritten characters and rather predictable plot, so that, in the first half in particular, it’s very easy to just sit back and enjoy the brilliant dialogue and the way the students clash and compete for approval. But in the second half the easy comedy is toned down and replaced by a series of clichés – everyone’s sleeping with each other, secrets from the past are dragged up, repressed irritations are blurted out. That’s not to say that it’s not enjoyable – it’s punctuated with enough laughs that you don’t really see the cracks whilst you’re watching and instead just go along with it, but at one point Allam’s Leonard asks Martin “Are we done with the soap opera?”, and I couldn’t help wanting to ask the same question. The play would be much more successful if Rebeck took more time to push and develop her characters and their relationships rather than putting so much focus on the overwrought plot, but Seminar‘s offering of snarky one-liners and hugely enjoyable performances makes for an entertaining if not enlightening evening.

Seminar is playing at Hampstead Theatre until 1 November. For more information and tickets, see the Hampstead Theatre website.