If Michael Cunningham hadn't already written "The Hours," "Specimen Days" would be a bold and innovative novel that didn't quite work. But following on that graceful, Pulitzer Prize-winning paean to Virginia Woolf and the women who love her, Cunningham's latest effort--starring Walt Whitman in the Woolf role--feels like a strained and familiar novel that doesn't quite work. Like "The Hours," "Specimen Days" follows three groups of similarly named characters--in this case, a man (Simon), a woman (Catherine, Cat or Catareen) and a child (Luke or Lucas)--through three eras: New York City during the early industrial age, after 9/11 and in a postapocalyptic future.

Linking the three novellas is Whitman's "Leaves of Grass." In the first and strongest section, "In the Machine," a sickly, Whitman-quoting teenager tries to avenge his brother's death--and win the love of his bereaved fiancee--by getting a job in the factory where he was killed. On the street one day he meets the poet himself, who implores him to go "where the buildings diminish and the grass begins." In "The Children's Crusade," a police psychologist tries to uncover a ring of child suicide-bombers brainwashed by a woman who calls herself "Walt Whitman" and has plastered his verses on their apartment walls. And the silly "Like Beauty" features an androidlike creature programmed with a poetry chip that compels him to spout random lines of--you guessed it--and may, in fact, help make him more human.

Cunningham's writing is as lyrically evocative as ever: a woman caught in a burning building "shrieked toward the earth, trailing ribbons of flame." And his willingness to experiment with different genres (sci-fi!) shows real courage and ambition. But their vast disparity works against his attempt to connect the novellas. Woolf, Whitman... Now is the hour for Cunningham to move on.