“There’s not much more to be said on that subject - betrayal,” says one character to another halfway through this play. It’s a cocky joke from playwright Harold Pinter, who says plenty on the subject throughout his tense and engrossing script. But it’s true that this particular form of betrayal - an extra-marital affair - isn’t the freshest of plot devices. So Pinter adds a twist, which must have seemed groundbreaking on the play's debut 40 years ago: telling the story backwards.

We start in 1977, with a meeting of former lovers, defined by nervous forced dialogue and the unmistakeable burden of the past. Next it’s 1975, and we see how and why the affair ended; then we go back further, to understand the way it blossomed before the frost set in. Only at the very end, when we’ve reached the sixties, do we witness its inception - the original sin of betrayal. It’s a clever and satisfying technique, which delivers more and more intriguing mysteries even as it resolves them; the question is never what has happened, but why, and sometimes when.

A lot of secrets emerge on-stage - layer upon layer of revelation - and often, the unspoken reactions tell us more than the confessions themselves. Under Roger Kay's direction it's done subtly, with the greatest depths of expression delivered in silence, and to appreciate the performance to its fullest it’s best to watch the character who isn’t speaking. Sophie Dearlove is particularly effective during a scene in a Venice hotel room, conveying - almost wordlessly - the creeping chill of realising that her husband’s inconsequential prattle is a signal that she’s been found out.

Indeed, Dearlove is compelling throughout, from her cold sharpness as she ends the affair to her silent disdain at an outpouring of casual misogyny. As her husband Robert, Duncan Henderson is intellectual and superior - playing his role, as the script demands, with a terse, condescending wit. (Just a couple of lines betray Robert’s anger, and Henderson truly makes them count.) Neil James completes the triangle as the cuckolding Jerry, less self-assured than the others and gently vulnerable; it’s to James’s credit that Jerry attracts our sympathy, even though what he’s doing is so terribly, unambiguously wrong.

But this is a script which nobody emerges well from, with a tangled mess of deceit and hypocrisy gradually unwound as the story flows backwards through time. Each character has secrets, of many different kinds - and the effort of remembering who knows what heightens the suspense of waiting for the careless word or deed we know will give it all away. If you go to see Betrayal - and you certainly should - watch their expressions carefully. Because in the end, if you’re carrying a guilty secret, it’ll be your face that betrays you.