James Carpenter and Sarah Grace Wilson Photo by Kevin Berne

Heisenberg begins strangely and abruptly, in London's St. Pancras station, in the moment after Georgie (Sarah Grace Wilson) has kissed Alex (James Carpenter) on the back of the neck, claiming she thought he was someone else. Rather than apologizing, Georgie launches into a manic attempt to engage the rather reserved Alex in conversation.

Georgie is clearly unhinged, lying ("I'm an assassin."), lying again ("I'm a waitress."), and then admitting she lied ("I made it up. I do that sort of thing a lot."), establishing herself in the very first moments of the play as highly untrustworthy. She disrespects social boundaries and conventions, delving deep into personal territory that would send any sane person (especially any British person—as Alex is, Georgie being a transplanted American) sprinting for the exits. But when you are a 75-year-old single man and an attractive, much younger woman kisses you and engages you in conversation, the sensible course of action might not be quite as appealing.

Just as Georgie's hyper-manic nature begins to wear on the audience, however, playwright Simon Stephens (who also wrote the brilliant adaptation of The Curious Incident of the Dog in the Night-Time) drives the narrative in a whole new direction. It's as if we've been racing along a mountain highway at high speed, when the road suddenly narrows, the guardrails disappear, and the brakes stop working. It's simultaneously thrilling and disconcerting. "Do you find me exhausting but captivating?" Georgie asks at one point. Yes, but not only her.

In addition to the excellence of Stephens' compact (and profanity-laden) text, this production of Heisenberg benefits from powerful performances by both actors. As Alex, Bay Area favorite James Carpenter displays a taut (and brilliant) restraint, both physical and emotional. Alex's posture is upright without being stiff, and every motion he makes feels intended, almost planned ahead. But his veddy British "keep calm and carry on" veneer masks a depth of character that is both surprising and welcome (as when he describes himself as "a deranged septuagenarian pooh bear with an unusual love of DJ Zinc").

This is in stark contrast to Wilson's Georgie, who seems in a state of perpetual flightiness, almost as if she is ready to bolt at any moment, escaping the chaos her mendacity creates. She fidgets and flits and talks almost unceasingly. Wilson somehow manages to make Georgie someone Alex, and we in the audience, love, despite the common sense that is telling us to run as fast as possible away from her.

True to the Uncertainty Principle referenced in the title, Heisenberg illustrates how we can never understand a thing perfectly. If we get too close to grokking one variable, another becomes less predictable. Heisenberg takes its audience to places both strange and familiar—but if you can relax and accept a little uncertainty, you're sure to enjoy the ride.

Heisenberg, through April 8, 2018, at ACT's Geary Theater, 415 Geary Street, San Francisco CA. Performances are Tuesdays-Saturdays at 8:00pm, and Wednesdays, Saturdays and Sundays at 2:00pm. Tickets (ranging from $15-$110) and more information available at www.act-sf.org.