It is a common dream: You are forced onstage, in front of an audience of strangers, and must perform a part you have not rehearsed. Last Wednesday, actor Aimee Bruneau lived this nightmare, performing in Tim Crouch's An Oak Tree opposite Theater Schmeater's artistic director David Gassner. An Oak Tree demands a fresh victim each night: The theatrical experiment was designed for one rehearsed actor and one unrehearsed actor.

Gassner instructed Bruneau where to stand and what to say. He ran the show and acted his half of the drama—though his performance lay flat next to Bruneau's freshness; her impulses, which brought her almost to tears in one scene, were her best director. At times he commanded her aloud or gave her a part to read, other times he whispered into her ear or a microphone wired to headphones she wore. "You're a father," he said as the play commenced. "Your name is Andy. You have cracked lips, a bloodshot eye." And he introduced himself, a hypnotist who accidentally hit Andy's daughter with a car, killing her.

An Oak Tree is more driven by theme than narrative. The actors play themselves, their characters, each other's characters: At one point, Andy is hypnotized, convinced that he is not only naked, but defecating in front of a crowd. In other scenes, the actors pretend to be themselves discussing the show, reading all the while from scripts. They end the play by facing the audience, speaking in second person, forcing us to become them. In this theatrical experiment, actor maneuvers actor and the hypnotist controls the hypnotized, exploring the boundary between puppeteer and puppet, and asking whether one is so different from the other.