Written by Kat Sandler. Directed by Stephen Drover. Coproduced by the Arts Club Theatre Company and the Belfry Theatre. At the Granville Island Stage on Wednesday, September 26. Continues until October 20

Playwright Kat Sandler won the 2016 Dora Award for outstanding new play for her jaw-dropping professional debut, Mustard. The Arts Club’s new coproduction with Victoria’s Belfry Theatre makes it easy to understand why.

The titular character, played by Andrew McNee, is the imaginary friend of Thai (Heidi Damayo), a very angry 16-year-old whose personal life and home life are disastrous. Thai and her mom, Sadie (Jenny Wasko-Paterson), are both still devastated that Thai’s dad walked out a year earlier. Sadie is self-medicating with wine and pills, while Thai is getting into physical fights at school and screaming at Sadie, and Mustard is forced to face up to the fact that in his own desire to be needed, he has overstayed his welcome and delayed Thai’s ability to grow up and cope with her feelings.

Sandler’s writing is so good and it holds up beautifully to director Stephen Drover’s decision to start big and stay there, every emotion and every confrontation epic and unrelenting. This isn’t wholly a criticism, because most of the time, the production’s broadness matches Mustard’s balance of arch whimsy and traumedy (trauma-informed comedy). But there’s also a lot of tenderness and nuance in Sandler’s script, and Drover’s pacing puts additional demands on his already hard-working cast.

Damayo, making her Arts Club debut, is fantastic. Thai’s anger is utterly believable, as are the familiar teenage mood swings—deliberately cruel to madly in love, utter despair to all-consuming rage. Wasko-Paterson is heartbreaking and hilarious, and she builds a bridge between the two effortlessly. Mustard is a physically demanding role, but it’s also an emotionally rigorous one, too, and McNee is brilliant. The play hinges significantly on his performance, and he’s flawless. Also, the chemistry between Wasko-Paterson and McNee is perfect, from their first startled meeting when Sadie discovers she can suddenly see Mustard to their sweetly off-kilter flirtation.

These performances are inspired by Sandler’s way with dialogue. I think one of the marks of a well-written play is the cast’s ability to navigate the language, particularly the swearing, and Mustard’s every F-bomb lands with precision. It’s also a play that sneaks up on you, and doesn’t provide any tidy resolutions or easy answers about love, family, and the lies we tell ourselves about loneliness, feeling needed, and the reality of growing up. Mustard is wonderful and weird, and it signals a powerful and welcome new voice in contemporary theatre.