"Fifteen years ago I killed my sister." Much of Adam Rapp's Nocturne, now playing at the American Repertory Theater, is as stark as this line. The work is essentially a symphony on the theme of these words. The nameless Son is a humdrum high school student when he accidentally runs over his nine year old sister with a car. He is plucked out of obscurity to occupy the foreground of a blood red stage, where he speaks for two hours on the topic of his sister, his family and his dissatisfaction with life in general, interrupted sporadically by dialogue largely vacant of meaning. The figure of the Daughter haunts the Son, often twinning his gestures or acting out key moments in the accident.

Even though there is a narrative, the play is mainly a study of a diseased mind. The Son thinks in music. He is a child prodigy at the piano, and his musings flit around the tones of baseball bats, humming power lines and clicking typewriters. But he becomes disillusioned with music after the accident. The piano is a lifeless manifestation of the comfortable suburban lifestyle that is wrecked forever.

The Son turns to words to replace musical notes. He unrelentingly assaults the ear with precise metaphors, dissecting every aspect of his dead sister: her body, her dress and her words. He floods every part of his life with pregnant description. The flow does not stop even when his father, in a post-accident moment of rage, sticks a gun in the Son's mouth. The only things immune to his touch are the names of the players themselves: the whole time it is only Son, Father, Mother and Daughter. Family members are the rocks upon which the Son's fragile shell of an ego crashes.

The style echoes the fact that Rapp wrote Nocturne when he was reading Faulkner. Although the Son never lapses into an inchoate stream, his monologue is a form of self-flagellation reminiscent of The Sound and the Fury's Jason Compson. In Nocturne the monologue is lyrical, moving with the sheer inevitability of a musical composition. Dallas Roberts' Son makes each word into a plaintive wail. Even when the character lapses into humor (at one point even mimicking stand up comedy), the humor's forced nature hints at more shocks to come. The subject matter is graphic and serious business.

The second half of the play is more conventional and elaborates on the Son's affliction. His mental tension becomes sexual impotence, as revealed in a sensitively executed nude scene. At times he has to endure pains even Candide never had to face, well beyond the point where it becomes implausible. And the fact remains that while nudity has shock value, the Son's angst shows him to be figuratively exposed throughout the whole first half anyway.

Also in the second half the function of words changes. Words, which had been a means of drowning the self, begin to provide solace. The Son writes a basically autobiographical novel that puts him in contact with a girl who revives him to some extent. When the estranged father reads the book, it enables communication at last, fifteen years after the accident. It allows the father to name his grief and thus attain power over it. For the Son, his literary persona becomes the edifice on which he will reconstruct his shattered life.

The weakest parts of the play occur when the Son lashes out in stock criticism of bourgeois society. When he flees to New York after the accident, he exults over his poverty and freedom in terms a college sophomore might use. Those moments do not do justice to the complexity of character wrought in the first half.

Overall, though, Rapp presents us with a sympathetic and memorable character. This is Rapp's first major production, and moments of naivet and self-consciousness in the work show it. Fortunately his pinpoint accuracy with language makes it an aural delight. Expect much more, and much better, from Adam Rapp in the future.