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By Lucy Prebble, directed by Mitchell Cushman. Through July 30 at the Coal Mine Theatre, 2076 Danforth Ave.

Better living through chemistry?

The pharmaceutical industry has been promising this for nearly a century, and debates about whether prescription drugs improve human life or are one big societal addiction enabled by Big Pharma rage on.

Lucy Prebble’s 2012 play “The Effect” translates such questions into a gripping drama currently having its Canadian premiere at the Coal Mine Theatre. Mitchell Cushman’s intense, inventive production goes a long way toward smoothing over some of the less plausible elements of Prebble’s script and is anchored by a stunning performance by Aviva Armour-Ostroff, leading a perfectly cast four-person ensemble.

The setting is a drug trial: two 20-somethings, Connie (Leah Doz) and Tristan (Aris Athanasopoulos) are drawn to each other while taking increasingly high doses of an antidepressant, but is their attraction natural or the effects of the medication’s dopamine? Armour-Ostroff plays Lorna, the doctor monitoring them, and Jordan Pettle is Toby, the celebrity psychiatrist running the trial.

Toby and Lorna’s complex past history adds emotional stakes to their intellectual and moral debates about whether depression is a disease and antidepressants its miracle cure (his position) or the symptom of larger concerns and related to external factors (hers). Meanwhile sexual energy crackles between Doz and Athanasopoulos as Connie and Tristan circle closer to each other, defying the trial’s rules but perhaps also playing into its larger agenda.

English scribe Prebble scored a major U.K. theatre hit with “Enron,” which imagined the circumstances leading to the bankruptcy of the American energy giant, and was a writer on the smash hit TV series “Succession.” She has a superb facility with believable dialogue, which actors can infuse with layered meanings and sometimes deadpan humour.

Cushman, renowned for his direction of site-specific performances, embraces the small size of the Coal Mine auditorium and, with his frequent collaborator Nick Blais (lighting, set and props design), essentially turns it into an immersive environment. Most of the action takes place in a rectangular playing area in the middle of two raked banks of audience seating, with the actors moving the slats of cleverly designed chairs to turn them into gurneys and MRI beds.

Cushman shrewdly choreographs entrances and exits and often has characters remain onstage while not active in a scene, which keeps the production pacy and underlines the ways the two halves of the story implicate each other. James Smith’s sound design and musical compositions add further emotional texture.

Boldly, a long scene is played in full darkness save a cellphone flashlight with the action extending up the theatre’s aisles and even onto its ceiling. There’s well-handled and extensive stage intimacy (co-ordinated by Aria Evans) and audiences should be prepared for stage violence.

The ingenious staging swept me into the storytelling and kept niggling questions about plot and theme largely at bay during the show, though they’ve not gone away afterwards. Wouldn’t there be external controls to protect participants as the drug trial takes a thriller-like twist? And the play falls into gender stereotypes in having the men mostly sparkle and seduce while the women self-question and suffer (that said, perhaps this bugs me because it rings so true).

All praise to Prebble, though, for writing such a gorgeously rich role for a mid-career actor as Lorna, whose highly principled demeanour and dry wit are the crunchy surface layer of someone with personal stakes in the mental health debates in which she so ferociously engages with Toby and Connie.

Armour-Ostroff’s performance is a slowly rising storm, initially so coolly good with the patients, little cracks of vulnerability showing in her exchanges with Toby, and then mounting toward a devastating release of emotion.

Pettle is almost unsettlingly convincing as the silken Toby, and Doz and Athanasopoulos engage apart and together as very different young people navigating a high-stakes situation and discovering new aspects of themselves and each other.

This intense, brainy, well-produced drama is bang on brand for Coal Mine and a strong end to their first season in their new home at Danforth and Woodbine. Bring a smart friend: you’ll want to keep talking about this one afterwards.