Pretty, twenty-year-old Mariposa has entered the U.S. from Honduras by way of Nuevo Laredo, without documentation. She now serves drinks and woos customers as a B-girl—sort of a dime-a-dance arrangement—in a shabby night-club on the east side of Austin, Texas. Rough work, it's at least giving her a start in America.

Between the norteño and cumbia songs the DJ plays, a smooth-talking Anglo out-of-towner who calls himself Bill shows up at the club one Saturday night to sit and casually chat with Mariposa. He smiles and sympathises; his flattery leads her to reveal the secret pain she has kept hidden so long. But Mariposa has no way of knowing that he's being hunted by police throughout the Southwest.

Even in Austin, far from the border, there are dangers more sinister than narcotraficantes or la migra.

LaSalle’s intense, haunting novel beckons readers into the shadowy lives of undocumented workers in the U.S. and the difficult choices they must face. Written as a single book-length sentence, Mariposa's Song is also a truly innovative achievement in the novel form itself, as it continually startles and satisfies with stylistic daring and sheer lyrical radiance.