We all know what the world is going to be like after civilization decays: It's a wasteland, usually arid (A Boy and His Dog, Mad Max), occasionally sodden (Waterworld), lightly populated (Omega Man), at least by humans (Planet of the Apes), and everybody goes in for that gnawed and stitched Flintstone clothing. Costner, who both directs and stars in The Postman, carefully incorporates all the aspects we expect to find in a movie version of the not-so-distant future, but he does one thing very differently: Post-apocalyptic movies are customarily cautionary tales, while The Postman is a feel-good movie.

It's the year 2013, and Gordon Krantz (Costner) and his mule Jake are wandering around a dry lakebed, trying to scrounge food and avoid trouble, basically reprising the first few scenes of the 1975 cult film A Boy and His Dog. Eventually, they have to wander into civilization to get supplies, and there arrives wickedness in the form of an army of bad boys led by General Bethlehem (Will Patton), a former copier salesman turned bridegroom of pure evil. He conscripts Krantz, hurts him, and then loses him in a stunning escape scene (reprised from an episode of Xena: Warrior Princess).

Krantz is just a regular guy trying to avoid trouble, okay? But roles keep being thrust upon him. First, he's a soldier; then he's a postman, due to a bag of mail he's found in an old Jeep. Krantz gets the notion to deliver the 15-year-old mail to the citizens of a nearby town in hopes of getting a free meal (which, in the future, will always consist of soup). For the hell of it, he throws in some messages of hope by mentioning the "Restored United States" and making the claim that he's been deputized by the new President. All this is a lie, of course. As Bethlehem points out, what they have going there is a feudal system of government.

But the citizens of the little town treat him like a hero. He's the first person they've met in years, it seems, who evokes the idea of cooperation, order and connection with the outside world. He claims the new President has a motto: "Stuff's getting better!" This is about the level of sophistication The Postman reaches for; this is about the level it grasps.

But there's something satisfying about the middle-brow range of The Postman. It can be corny, but it never stays painfully corny for long. It can be witty, but it never stays witty for long, either. The movie as a whole is much like Krantz' mule Jake, who's really smart for a mule, but he's still a mule.

And so, for three hours, The Postman plods on in its pleasing, middling way. Costner persists in being the most appealing unlikable actor working in the movies: You can always sense his shallowness, insincerity and inflated sense of importance, but he picks roles where this works for him. Here, he doesn't want to be a hero, and doesn't deserve to be--which is nifty, because you can tell he doesn't have it in him. (With The Postman, Costner will do for letter-carriers what Zsa Zsa Gabor did for lap dogs.) Patton is the perfect balance to this--a charismatic, sensitive guy who seems to nurture a kind soul beneath his evil exterior. Every time he does something nasty, it's a shock.

The two cavort through the wonderful set designs we can look forward to in the future. Bethlehem's army trains in a pit mine--an alien, forbidding-looking place if ever there was one--and at night they watch a scratchy print of The Sound of Music projected on a screen hung on one of the cliff-like walls. The hamlets Krantz discovers are neat, Rube Goldburg-type constructions wedged into pieces of old infrastructure--mines and dams and the like. Cool!