"The Effect". Burton Taylor Studio

Lucy Prebble’s ENRON told the story of a company falling to pieces. Her next play, The Effect, shows us the human brain doing the exact same thing. Both push their characters, whether corporate or clinical, to the limits of endurance, but The Effect has an extra, and potent, ingredient: love.

The Effect takes place over the course of a month-long medical experiment to test a new anti-depressant, during which two of the subjects, Connie and Tristan (played by Rose Martin and Alec Greene) become uncontrollably infatuated with each other. Is their passion down to the drug, or is it real? And is there any difference? Does man-made chemistry create these desires? Or does it merely release what’s buried inside but scared to come out and play? Is it the Truth, or just… the Effect? These are inescapable questions in an age when we are surrounded by machine-made impulses pounding at our vulnerable souls.

At the same time, the impact of playing God with people’s emotions inevitably affects those in control. Doctors Lorna and Toby (Robyn Hayward and Rohan Joshi) find that what happens to their human guinea pigs unleashes memories, regrets and desires of their own. It’s an all-out emotional melodrama caged by the trappings of scientific research. And – just to be clear – it’s completely brilliant.

I never thought it would be possible for a simple sequence of lighting fades to reduce me to tears. But in the central scene of The Effect, that’s what happens. Two people who have fallen in love, and who have tried to deny it, finally embrace each other, kiss, make love, and become one. In a series of tiny tableaus we see them in captured moments of affection, and the lights fade gently on each one, underlining their brevity, their fragility, and their significance. Perfect happiness doesn’t come along too often. When it does, remember those vignettes. Their intimacy has a physical poetry about it, bodies slotting and curving into each other, naturally combining in a way so pointedly resisted by the rest of the performance.

In fact one of the most remarkable things about this production is the way that, most of the time, the characters occupy their own discrete zones of space and movement. Connie is like a junkie doing cold turkey: fidgeting, awkward, jerky. Tristan has the fluidity that comes with total charm, a tennis player loping on the stage, teasing Connie out of her shell of uncertainty. Lorna, the psychiatrist in charge of their trial, tries to stand tall and strong, but only ever seems to occupy the very edge of the space, nervous to enter, wobbling on her heels, an inch away from crumbling herself. And Toby, the senior consultant preparing for his TED talk, always stands centre stage, the boxer controlling the ring. No doubt who holds the power here. 

Fennec Fox’s production, directed as ever by Josh Robey, is as powerful as anything they’ve done up till now – and this follows stellar productions of The Writer, The Flick, and Company in recent months. Fennec’s work is marked by a combination of technical mastery and sublime acting, and The Effect is no exception.

Like the carefully managed medical trial it depicts, everything about this production is judged to clinical perfection. The music – in fact let’s call it a soundscape, since it shifts and billows in pace with the actors – by Ice Dob, conveys both hospital-machine beeping reassurance and tsunamis of thudding reverberation, toying with our fraught nerves like an amused cat. Yusuf Naeem’s boldly bare set features nothing more than a sheet of plastic on the floor. It’s just antiseptic enough to remind us where we are, but open enough to make the characters feel exposed, bare and alone. It also makes the Burton Taylor look about twice the size of its usual self, which is both thrilling and disconcerting.

And Ted Fussell’s lighting is a paragon of both boldness and restraint (as his previous work on Under Milk Wood and Constellations promised). When Connie and Tristan are taking their pills, it’s all flashing red lights. But when they finally give in to their mutual yearning, it’s tender as an evening glow.

All this super-confident stagecraft creates an arena for outstanding acting to thrive. And that’s exactly what happens here. Greene, Martin, Hayward and Joshi are all riveting to watch. Doubts and hopes flicker across Martin’s eyes like autumn clouds; Hayward’s professionalism crushes her humanity before our gaze; Joshi’s Harley Street smugness leaves him questioning his own morality; and Greene calibrates his puppyish flirting as it ramps up to obsessive desire. What happens to him at the end of the play recalls the climax of that other masterpiece of medical mishaps, One Flew Over the Cuckoo’s Nest – and if he goes on to emulate Jack Nicholson’s career in other ways, save me some popcorn.