Oh no, surely not another bunch of 30-somethings going to pieces in the dissolution of dreams market? Yes. But Lanford Wilson’s 1970 Off-Broadway play (re-written for the Circle Rep in 1976) proves a real corker.

And it’s given a tremendously taut and enthralling production by Simon Curtis, the former Royal Court director (notably of Jim Cartwright’s Road), returning to the stage after a long and distinguished stint in television (Cranford and Stephen Poliakoff films).

Two Chicago couples cross-fade into each others’ lives on the same utilitarian sitting room set of sofa, standard lamp, drinks cabinet, French windows and Balinese puppet on the wall. Director Curtis and designer Peter McKintosh, artfully abetted by Guy Hoare’s lighting and Adam Cork’s soundtrack, make the intersections both graceful and plausible.

The acting is stylish and magnificent from a cast you’re not quite sure who they are: visiting American actor Jason Butler Harner is superb, both haunted and driven, as the shooting star political lawyer Alex whose wife Gabrielle, played with unrecognizable, vulnerable hesitancy by Charlotte Emmerson, is talking to the roast and teetering on the brink.

Carl, his buddy and fellow alpha male - this play has marked elements of Edward Albee and Neil LaBute - is a going-to-seed college quarterback who’s a successful construction developer and who, shockingly in Jason O'Mara’s flip delivery, is bugged by a child’s tragedy and believes people can be brought together in extreme circumstances only.

Carl has discovered that his wife Mary - whom Geraldine Somerville, best known these days for being in the Harry Potter movies, plays as a dead ringer for Julianne Moore at her most hard-edged and soignée - is having an affair with his own chief accountant.

The foursome return from a screening of Deep Throat (“I’ve never felt so over-dressed,” says Mary) after Alex has complained about being “raped” by his wife every night and owned up to his affair with a 17-year-old girl.

These are people adrift in their own quagmire of sexual degradation and disgust; only Gaby can genuinely claim to be a victim, and it’s a rum and rueful quadrille they dance out. There is, inevitably, a price to pay. A tragic climax is followed by the prospect of endless night-time desolation.

It’s all brilliantly done. The Donmar has surely revealed a modern American classic, and one that is as much a surprise as it is a pleasure to discover.