The reason for Cowboys & Aliens — the justification for it, the appeal of it, the whole point of it — is contained in the title.
Take a cowboy movie, add space aliens. That's a gimmick that could easily have exhausted itself after 20 minutes, but director Jon Favreau, a team of screenwriters and some well-cast actors keep it alive, and the result is a crowd-pleasing summer movie with more wit than most.
The more you know westerns, the more you'll enjoy Cowboys & Aliens. Every western cliché is pumped up and blown out, not only the clichés of story but of character, costume and set design. Sam Rockwell, as a merchant, shows up with the little round spectacles and plastered down hair that you've seen in a hundred movies. Paul Dano as a spoiled drunken brat on a rampage starts shooting up the town, like every obnoxious skinny kid with a gun from a thousand westerns. And the shots of the rickety old town, a few structures in a vast nothingness, are a little more forlorn than usual.
At the center of it all, of course, is a lonesome stranger with a dark past. This time it's Daniel Craig, as stern and unsmiling as Clint Eastwood, who wakes up in the movie's first scene in the middle of nowhere, with an elaborate metal bracelet on his wrist and suffering from amnesia. But he does remember how to fight. When he takes down four creepy guys - they're filthy with long beards and look like something out of western central casting - the audience settles in for a good time.
For the most part, Cowboys & Aliens delivers. Favreau has a subtly satirical sensibility that can suggest absurdity simply through camera placement, as when Craig stands framed in a doorway, like some western God, and then says, "Hello?" - sounding just a little unsure and ridiculous. The script is sprinkled with funny moments for viewers in the know. At one point, an exasperated Rockwell turns on someone and says, "Why don't you sing a song, cook some beans, do something useful!"
But the movie's most inexhaustible source of delight is Harrison Ford as a cranky old entrepreneur in an Indiana Jones hat. It's a given in every Ford movie that he's ticked off about something. The trick is to give him a reason to be so surly. Space aliens taking his son? Alien death rays burning up his cattle? OK, these are good reasons. Ford doesn't exactly play for laughs, and in fact the movie provides him with several dramatic moments that he seems to relish. But Ford knows who he is on screen and what he has come to mean over the decades. He knows exactly where the laughs are, and he nails every one of them.
On the downside, Cowboys & Aliens is not the western answer to Inglourious Basterds. Here, genre isn't exaggerated to jar audiences from their complacency or to discover new truths. The movie combines cowboys with science fiction only for the sake of doing it, for the fun of it. Like the novel Pride and Prejudice and Zombies, you already have the best joke going in. Lacking an overarching purpose or viewpoint, the movie is no better than it happens to be in the moment, and there is a 20-minute stretch, about a quarter of the way in, that drags.
But Cowboys & Aliens gets better as it goes along, and benefits from a director with a solid command of tone. The actors may know they're in a comedy, but the characters certainly don't. That's an important difference that allows us, once the premise's novelty has worn off, to care whether Daniel Craig can rescue a very somber Olivia Wilde from the clutches of an alien space ship, for example. Or to maintain a reasonable interest in the fate of a humanity threatened by gigantic, green, snorting monsters.
mlasalle@sfchronicle.com