Keanu Reeves and Jennifer Connelly team up for a modern-day update of the '50s sci-fi classic 'The Day the Earth Stood Still,' in theaters December 12, and ET has a first look! Will Keanu's character save the human race? Or destroy it?

"The life of the planet is at stake and the humans are killing it, so I've come down to judge them, to see if the problem needs to be removed," says Keanu.

In the movie, the 'Matrix' trilogy star plays Klaatu, a humanoid alien who lands on earth to warn world leaders -- with the help of an indestructible robot -- to stop warring or the human race will be annihilated by watchers from above. Jennifer is the astro-biologist who may hold the key to mankind's survival.

"He's denied access to world leaders, but he ends up having a relationship, and relationships," explains Keanu, "and through those relationships he comes to see another side of [the human race]."

"She figures out why he's here and what's going on, and it's incredibly devastating," says Jennifer of her character. "She's a really brave, determined character who just does everything she can to change his mind. That she meets a being from another planet is extraordinary; that it's taken this human form is all the more extraordinary; that he's sitting in her car and she's driving him around is absolutely unfathomable."

Arriving at the height of McCarthyism and the atomic age, the original 'The Day the Earth Stood Still' capitalized on the growing fears in the post-war atomic age and made the giant silver robot "Gort" one of the most iconic images of '50s sci-fi. Klaatu, Barada, Nikto!

Watch ET for more with Keanu and Jennifer Connelly in 'The Day the Earth Stood Still'!