Stumbling across a stark, black-and-white landscape, a volatile woman spits tirades and muses over verse, while performing occult ceremonies at once nonsensical and terrifyingly symbolic of the obsessive and possessive despair that has overtaken her.

“4:48 Psychosis,” which was written by Sarah Kane shortly before her death in 1999, goes up this weekend in a beautiful production directed by Marie Ostby ’07. This epic descent into incoherence is an articulation of a suicide’s mind, the fickle, fascinating passions of a tortured, ranting psychology.

As the only actor on stage, Molly Fox ’08 performs an extended monologue, shifting rapidly between the diverse facets of the identity presented by Kane’s work. She has mastered an immensely difficult role, one that requires her to converse with silence, scream at clothing and whisper sweet nothings to mannequins. She executes perfectly what would be absurd, even hilarious, in weaker dramatic hands. The audience leaves the theater with a conviction of having seen something miraculous.

Fox has a rare command of emotion. She can evoke tears in one instant and terror in the next. One becomes frustrated by the necessity of blinking, as every flicker of her eyes expresses some hidden, exhilarating thought. Even more impressive is this talent for controlling a theatrical space: Her emotional state fills the shadow-drenched room; the atmosphere, even the light, conforms to her flawless, controlled expression; if she stops speaking, sound ceases to exist for the audience.

The stage is her expanded mind, populated with staring male manikins, a cage and shadows. Yet the audience does not see Fox as if through a window. It is as if the audience is contained in her mind, scrutinized by the same paralyzed and paralyzing stares of the mannequins, two of which stand among in the back row. Our proximity to her, our immersion in her terrifying little world of woman is emphasized when she enters the audience, speaks from behind us, paces among us.

The play is at once an expression of her “abnormal” psychology and a scathing attack on the medical culture that created that “abnormal” label. Fox harps on the insanity of the sane, the incomprehensible array of doctors that see disease instead of despair, that fling Prozac futilely at the monstrous self-loathing of the “mentally ill.”

In one striking scene (though scene division is appropriately indistinct in “Psychosis”), Fox’s doctor, represented by a monotone recorded voice that, like a god, drawls from the ceiling, breaks down. For the first time, the doctor sheds her “professionalism” to express a poignant, “abnormal” thought. This moment suggests our proximity to Fox’s character; that boundary between the sane and the insane is narrow, perhaps non-existent.

That intimacy is perhaps the play’s strongest quality. One expects to be horrified by Fox, to pity her diseased condition. But she is utterly human, a Protean amalgam of our emotions. There is nothing insane in her unrequited love, in her inability to suppress the painful thrill of proximity to one who feels nothing for her. There is nothing insane with her exasperation over a world that seems irreconcilable with her mind. Anyone can feel such emotion; anyone can feel the weight that is crushing her.

The unnatural quality of this theatrical experience is reminiscent of the core values of theater, a medium inherently surreal that thrives in a sort of absurdity and experimentation. The play’s brilliant, articulate eccentricity reminds the audience that it is not the bland mediocrity to which they’ve become accustomed.