So let's try to get this straight.

In "The Time Traveler's Wife," Eric Bana plays a guy named Henry who jumps around the past, present and future, only he can't control where or when he goes. Supposedly, he also can't control how he gets back where he came from, except for when he tries certain tricks to place himself in a state of mind to time travel. Even then there's no way to guarantee which version of Henry will show up: the same one who left or a younger or older version of himself.

Still, he manages to hold down a job at a Chicago library and maintain a makeshift apartment. The only constant seems to be that when he shows up at his destination, he's always naked. (Somehow, Henry has found time between his travels to hit the gym.)

Hunky as he is, he'd be a frustrating guy to fall in love with, or even date. Women like stability, you know. But Rachel McAdams' character, Clare, must be made of stronger stuff than the rest of us, because not only does she tolerate Henry's pesky inconsistency, she believes he's her destiny, and that he has been since the first time she saw him as a precocious 6-year-old girl (played by Brooklynn Proulx). The core of "The Time Traveler's Wife" is their struggle to stay together.

Director Robert Schwentke's film, based on the Audrey Niffenegger best-seller, breezes through their relationship, including the fact that Clare and Henry's meet-cute is more like a meet-creepy. He's a 30-something man who shows up wearing no clothes in the meadow behind her parents' house, asks to borrow her picnic blanket and just starts talking to her. This doesn't freak her out at all — where is the stranger-danger lesson, people? — presumably because she knows, even at this tender age, that she is cosmically meant to be with him.

Maybe it's more plausible on the written page — or maybe you just have to be a hopeless romantic and willing to shut off the part of your brain that craves logic to enjoy this. But strangely, in the script from Bruce Joel Rubin (an Oscar winner for "Ghost," a supernatural love story that actually made sense) the time-travel gimmick supersedes any sort of substance, depth or character development.

Bana and McAdams try their best to win us over to this complicated conceit with enormously earnest performances. McAdams shows some of the same dramatic capabilities that helped make her a star in "The Notebook." As for Bana, this is a rare and welcome opportunity to seem him play the romantic lead, for which his dark good looks and strong presence would seem to make him a natural. And the ever-reliable character actor Stephen Tobolowsky grounds things somewhat as the geneticist who tries to help Henry and Clare forge some sort of normal life.

Still, we're left wondering afterward, how do these people feel about this extraordinary situation in which they've found themselves? In theory, indeterminate time traveling would wreak havoc with even the most mundane daily activities: grocery shopping, sitting at a red light, parent-teacher conferences.

Speaking of which, Henry and Clare eventually have a daughter to whom they pass on the time-travel gene, but it doesn't seem to bother the kid, either. Really? You're 5 years old, playing hopscotch with your buddies during recess, and poof! You disappear. Wouldn't that be slightly disturbing?

"The Time Traveler's Wife" doesn't seem interested in crawling inside her head, either. It's too busy trying to tug at our hearts.

"The Time Traveler's Wife" is rated PG-13 for thematic elements, brief disturbing images, nudity and sexuality. Running time: 107 minutes.