Ms. Blanchett is Daisy, a dancer, bohemian and all-around free spirit who ages gracefully, before our eyes, into a stately modern matron and then into a wasted, breathless old woman. Mr. Pitt, for the most part, plays Benjamin, who is born, looking like a man in his 70s, into a prominent New Orleans family in 1918. I say for the most part because near the end of the movie Mr. Pitt is replaced by younger and younger children and also because, at the beginning, he is evoked by an uncanny computer-generated confection that seems to have been distilled from his essence. This creature, tiny and wizened, is at once boy and man, but in every scene the ratio is readjusted, until the strapping figure of a familiar movie star emerges, gradually and all but imperceptibly.