Scott Wentworth and Judith Ivey Photo by Kevin Berne

Such are the laughs that filled the theater on the opening night of Harold Pinter's The Birthday Party at American Conservatory Theater's Geary Theater. For Pinter was a genius at creating bubbles of nervous tension, bursting them with odd or confusing or seemingly insipid lines—but which often serve to reveal deeper, hidden layers of unease.

The Birthday Party is one of Pinter's earliest plays, and its layers of unease are multitudinous. Nothing is quite as it seems—or is exactly as it seems, but Pinter never gives us the information we need to discern fact from falsehood.

The action takes place in a British seaside resort town, in a downscale boardinghouse run by Meg (Judith Ivey) and Petey (Dan Hiatt). But is it really a boardinghouse? There's only one tenant (Stanley, played by Firdous Bamji), and while he claims it isn't a boardinghouse, Meg insists people come because it's "on the list." And are Meg and Petey really that simple? Their dialogue in the first scene is almost entirely composed of comments on things that are self-evident: "Are you back?" "You got your paper?" "Here's your cornflakes." "It gets light later in winter."

Thanks to stellar performances from Hiatt and Ivey, this seemingly inane banter has an undeniable comic charm. But when Stanley appears (unshaven, in pajamas and a robe), and hears from Petey that two men inquired about rooms for let in the house, his reaction cranks the anxiety to a new level. Stanley deflects the tension back to Meg, frightening her with an invented (or is it? With Pinter, one never knows) tale of a mysterious "they," coming in a van, with a wheelbarrow. But when the two men (Goldberg, played with smiling menace by Scott Wentworth, and McCann, played by ACT regular Marco Barricelli) do arrive, Stanley signals his fear by slipping out a back door, unseen by the two men who menace.

Very little happens, plot-wise, in The Birthday Party. Leaving the theater I overheard more than one patron ask "what was that about?" But this play, often described as a "comedy of menace"—like much of Pinter's work—isn't about what's happening on the surface. It's the subtext hidden beneath the meager plot and unreliable characters that provides the thrills, keeping you on edge for nearly two and a half hours.

Carey Perloff's direction is crisp, and her cast—to a person—is marvelous. Despite the almost minimalist nature of Pinter's dialogue, each exhibits a broad dynamic range of emotion, and expresses that emotion with subtle delicacy or broad physicality as required. Two-time Tony Award winner Judith Ivey is especially effective as Meg. As mistress of the house, the action seems to revolve around her, even when the action is not specifically about her character. The goofy rictus of a smile she has pasted on her face for much of the evening is infectious: from the moment she walk on stage, I could almost feel cheeks lifting and lips parting all around the theater.

The other standout is Scott Wentworth as Goldberg. His performance offers a master class in cognitive dissonance: handsome and charming, with an ability to drop compliments in just the right places, belying a sense of peril that surrounds his character like a sickly, threatening cloud.

Nina Ball's set provides a suitably dingy backdrop, with its low-rent furnishings and fixtures, stained surfaces, and hideous—yet somehow restrained—wallpaper. It's the sort of place most people would want to immediately leave. But despite its wide-open nature, it somehow manages to still feel claustrophobic and confining.

Laughter may be the best medicine, but Pinter has provided no spoonful of sugar to help you get it down. But that doesn't mean it's not just what the doctor ordered.,/p>

The Birthday Party plays through February 4, 2018, at ACT's Geary Theater, 415 Geary Street, San Francisco. 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.