It's not people time-traveling in this film, but letters placed in a mailbox. Alex (Reeves) is living in a lake house designed by his father, and he discovers a letter from alleged former tenant Kate (Bullock) requesting that her mail be forwarded to her new address. Odd thing about the letter is that it is dated 2006, and Alex is occupying the year 2004.
Yes, some sort of miracle is taking place, and the mailbox is magical. There are times where the two characters exchange notes one after the other, with the little mailbox flag raising up each time a letter is placed within. (Funny ... the flag goes up as if an invisible hand is lifting it, but the mailbox lid stays shut. If we can see the flag on the mailbox being lifted by an invisible person in the future or the past, shouldn't we also see the moment when they open and close the lid? Never mind.)
When the two realize they are truly communicating with somebody in a different time, they deal with it in a rather mature and accepting manner: They fall in love with each other's words. They don't freak out; they don't think they are crazy; no psychiatry is required. They just deal with the notion of being in love with somebody impossibly out of their grasp and get on with it.
Alex constructs a rather romantic tour of Chicago for Kate, and they take it at the exact same time two years apart. (Alex leaves some graffiti on a wall for Kate to read in the future which, I feel it is my duty to remind you, is a very serious crime.) The two, through a series of coincidences, wind up living with the same dog. When Kate talks about missing the trees from the lake house, Alex plants one by the entrance to her new apartment. It magically springs up in the year 2006 while Kate is perched just a few feet away. Damn thing could've killed her.
Reeves and Bullock don't share too much screen time together. They do have a very good scene where Alex tracks Kate down in the year 2004 (she doesn't know him), and they manage a brief romantic encounter that Kate has forgotten in the future. The two performers are good on screen together, and it's their likableness that makes the movie tolerable, even when it gets ridiculous or a little slow.
Christopher Plummer is great, yet again, as Alex's career-obsessed father. Chugging coffee and quietly yearning for his son's forgiveness regarding matters with Alex's deceased mother, Plummer makes a memorable character out of just a few minutes. It's amazing how much dimension the man can put on the screen with just a few lines. The rest of the supporting cast isn't nearly as memorable, but they perform their parts admirably.
There's a mystery in the movie that is very easy to solve, but it doesn't matter. I did like the way the film ended (there were tears, and actually some applause, at the Saturday-night screening I attended). Yes, it's implausible and stupid in places, but movies like The Lake House are allowed to be a bit silly. I gave a damn when the protagonists kissed near film's end, so in my book, the film succeeded in what it set out to do.