Kate (Sandra Bullock) who once occupied an unusual lakeside home begins exchanging love letters with its newest resident, Alex (Keanu Reeves). When they discover that they're actually living two years apart, they must try to unravel the mystery behind their extraordinary romance before it's too late in "The Lake House."

Kleenex won't be necessary for watching the wannabe weepy "The Lake House," but some sort of pain reliever is essential — because trying to determine whether this time-travel romance functions logically will seriously make your head hurt.

Without knocking ourselves out too much, let's give it a shot.

Keanu Reeves and Sandra Bullock star as the successive inhabitants of a cozy, cool-looking lake house — made of glass and standing on stilts — hidden along a quiet little section of coastline outside Chicago.

Reeves (as architect Alex Wyler) moves in after Bullock (as doctor Kate Forster) moves out. They drop perfunctory letters in the mailbox for each other about forwarding mail, some items left in the attic, etc. Soon they realize, though, that Alex is writing from 2004 and Kate is writing from 2006 — exactly two years apart from each other, to the day.

But wait: Didn't Alex move in AFTER Kate?

Regardless of whether you can go with this, Alex and Kate can — easily. In no time the letters turn flirty, then intimate, until both realize they're falling in love. When her boss at the hospital (Shohreh Aghdashloo) asks whether she has a boyfriend, Kate confesses with a sheepish smile, "It's kind of a long-distance relationship."

It calls to mind that line from "The Purple Rose of Cairo," when Mia Farrow says of the pith-helmeted actor who's walked off the screen and into her life, "I just met a wonderful new man. He's fictional but you can't have everything."

Trouble is, Woody Allen's "The Purple Rose of Cairo" is a comedy. Alejandro Agresti's "The Lake House," based on the South Korean film "Il Mare," is not — not intentionally, that is.

But wait: Early in the movie, a young man with dark hair is hit by a bus while crossing a busy street, right in front of Kate. And before that, you may have noticed on your way into the theater that on the poster for "The Lake House," Reeves is hovering behind Bullock, looking more pasty and vapid than usual.

Could Alex be ... dead?

If so, you're watching "Ghost" meets "You've Got Mail," two movies that were sentimental enough individually and did not need to be combined into one big blob of sap.

Then again, if he's dead, how can he leave an annotated map for Kate to guide her on a tour of all his favorite spots in Chicago? You need a flow chart to figure it all out — and you shouldn't, considering that the screenplay comes from David Auburn, the Pulitzer-Prize and Tony-winning writer of the play "Proof."Granted, either you're surrender to this sort of conceit from the beginning, or you're not. But if you enjoy going to the movies to be swept up by romance, the film should at least have the fundamental decency to make sense.The way Kate and Alex communicate, for example: Sometimes they have to place the letter in the mailbox, raise the flag and wait for the other person to reach in and read it. Sometimes they're talking to each other — out loud, in real time, while sitting on the same bench — as if through some sort of telepathic instant messenger. Other times, poof! A letter just magically materializes in a character's hands.Again, this is where the migraine-strength pain reliever comes in handy.Theoretically, part of the allure lies in watching the stars of "Speed" team up again in a totally different way.The one scene in which they do physically occupy the same space — sitting side by side on the porch at a party they're both attending in 2004 — does provide some sparks, not only because it's so long in coming but because they do look great together. (Christopher Plummer also livens up a few scenes as Alex's cantankerous architect father.)But in reality, all this does is make you wish a bus would come barreling through the production at 50 mph.