Time traveling may sound fun and rewarding, but it's actually sort of a grind. Sure, you can zip back to the past on occasion and briefly enjoy the company of long-gone relatives. But you complete the journey buck naked and physically depleted, and often the whole experience ends with someone trying to arrest you or beat you up.

Such is the hectic existence of Henry DeTamble (Eric Bana), a Chicago librarian who finds himself jolted around in time against his will. His mother's accidental death kick-started Henry's time traveling as a child, and his condition leaves him isolated and lonely until a lovely young woman named Clare (Rachel McAdams) bumps into him in the library. Gazing at him with a heady mixture of adoration, lust, wonder and unabated joy, she changes his life completely when she tells him she's known him forever and hints rather broadly that their futures are entwined.

Adapted from what can only be labeled the fanatically beloved novel that became a book-club must read, The Time Traveler's Wife is a dizzying blend of romance and science fiction, with emphasis on the romance. The movie is slightly more sappy, and the characters are necessarily less fleshed out than they are in Audrey Niffenegger's dazzling novel, but neither shortcoming detracts from the film's appeal. The screenplay sets out the rules of time travel succinctly (Henry can't control where or when he goes but tends only to travel around his life span), and scenes dissolve into blackout too often. But the script excises any fat with precision, simplifying more complicated entanglements from the book and cutting right to the heart of Niffenegger's themes about the role of fate in our lives and how true love can endure some serious tests of time.

McAdams and Bana are enticing as a couple whose domestic problems are distinctly original. You think you have issues with your significant other? Try planning a wedding when the groom tends to vanish under stress and return with no clothes on. All this nudity means you see more of Bana than you expect, though perhaps not as much as you might wish.

Not surprisingly, The Time Traveler's Wife eventually takes a turn for the weepy, but screenwriter Bruce Joel Rubin balances the melancholy aspects with a solid sense of humor. (Like Niffenegger, he also deftly avoids any unsettling moments in the scenes between the nude Henry and Clare as a child.) The movie will probably make you cry, but inducing tears is not its sole purpose. Its true aim is to remind us of the patience of the human heart.

Cast: Eric Bana, Rachel McAdams, Ron Livingston, Jane McLean, Arliss Howard, Brooklynn Proulx.Director: Robert Schwentke.

Screenwriter: Bruce Joel Rubin. Based on the novel by Audrey Niffenegger.

Producers: Dede Gardner, Nick Wechsler.

A Warner Bros. release. Running time: 107 minutes. Thematic elements, brief disturbing images, nudity, sexuality. Playing at area theaters.