I like Keanu Reeves myself — he has a unique star presence. But the nobody-home screen persona his detractors grouse about is not to be denied in "The Day the Earth Stood Still," a boldly mediocre remake of the 1951 sci-fi saucer-man movie. Here, Reeves never cracks a smile, hikes an eyebrow or, for all we can tell, draws breath. There may be puddles of spilled beer more expressive.

Not that his role allows for a lot of latitude in this regard. Reeves plays Klaatu, an interstellar emissary from somewhere or other who's come to Earth to ... well, more about that in a moment. Klaatu touches down in New York's Central Park, not in a standard spaceship like the one in the original movie, but in a big shiny silver ball that looks like nothing so much as a giant Christmas-tree ornament. He's brought along a towering robot bodyguard called Gort, who's only marginally less gregarious than his deadpan master. They're welcomed by the traditional contingent of itchy-fingered soldiers and goggling scientists, among them astrobiologist Helen Benson (Jennifer Connelly, who knows why?). As Helen approaches the ornament with a gesture of welcome for Klaatu, one of the soldiers naturally shoots him, and very quickly the luckless visitor is spirited away to a military lab for inspection and interrogation. As if any such puny human installation could contain him (see trailer).

Klaatu has not come alone — other alien arrivals are being reported around the world. The secretary of defense (Kathy Bates) is upset about a military satellite that's gone missing. ("They know everything about us now!") But the head scientist on the case (Jon Hamm of "Mad Men") is more concerned about Helen. (Although not too concerned; this is a movie that rates zero on the sexy meter.) Meanwhile, Helen's pouty stepson, Jacob (Jaden Smith, son of Will), is entirely focused on being a super-cute plot annoyance.

But what does this Klaatu fellow want, exactly? In the 1951 movie, he'd come to warn us to cut it out with the atomic weapons or our planet would be vaporized for the good of the universe. His message now, however, is more up-to-the-minute: "I came to save the Earth," he says. "This planet is dying. The human race is killing it." An intergalactic Al Gore, great. The solution, he says, isn't to death-ray our dying orb, but to terminate its messy populace. Talk about Earth First.

Klaatu announces that the countdown to annihilation has already begun. To ensure that a mistake isn't being made, though, he decides to have one last consultation with a fellow alien, Mr. Wu (James Hong), who's lived as a mole in the wilds of New Jersey for the last 70 years. (That they meet in a McDonald's, and converse in crafty subtitles, is the most wonderfully loopy part of the picture.) Wu confirms that the locals are a hopeless lot ("and they won't change"), yet he kind of likes them anyway. Also weighing in on the wait-a-minute side of the argument is an academic named Barnhardt (John Cleese in a sad cardigan), who's won a Nobel Prize for his work in "biological altruism" (a very Pythonian name for an actual subject of scientific inquiry). Barnhardt urges some cutting of slack for the human race, and Klaatu — after tamping down a hurricane of vicious, globe-gobbling CGI — decides that a second chance may well be in order. But, he warns, "It would come at a price to you and your way of life." His new human friends — with visions of Priuses dancing in their heads, no doubt — reply with a message straight from the heart of Hollywood: "We'll try!"

It should be noted that at no point in this very silly movie does the Earth actually stand still. You may need to reboot your brain on the way out of it, though.

Don't miss Kurt Loder's reviews of "Gran Torino" and "The Reader," also new in theaters this week.

Check out everything we've got on "The Day the Earth Stood Still."

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