Garrett Adams, an uptight behavioral psychology professor who refuses to embrace the 1960s, is in a slump. The dispirited rats in his latest experiment aren't yielding results, and his beloved Yankees are losing. As he sits at a New York City bar watching the Yanks strike out, he knows he needs a change.

At a Columbus Circle bookstore he meets a mysterious young woman, Daphne, who draws him into the turbulent and exciting world of Vietnam War protest politics and the music of Bob Dylan and the Beatles. He starts to emerge from the numbness and grief over his father's death in World War II.

When Daphne evolves into four separate versions of herself, Garrett's life becomes complicated as he devotes himself to answering questions about character and destiny raised by her iterations. His obsession threatens to upend his relationship with Caroline, a beautiful art historian, destroy his teaching job, and dissolve his friendship with his old pal Jerry.

The Daphnes seem to exist in separate realities that challenge the laws of physics and call into question everything Garrett thought he knew. He must decide what is vision, what is science, and what is delusion.