In 2012, opening Friday, the planet gets another cataclysmic wedgie from disaster filmmaker Roland Emmerich (Independence Day, The Day After Tomorrow), who this time forgoes hostile aliens and rapid climate change in favor of an even bigger problem: The Earth implodes.

It's the latest movie to test the theory that when one character dies, that's drama. But when billions of people are swept away like crumbs into an unfathomable abyss, that's entertainment!

"There's a line you have to walk," says John Cusack, who plays an everyman who tries to save his two kids and estranged wife (Amanda Peet) as the ground crumbles beneath their feet. "I think there's a catharsis, the same as a roller-coaster ride. You want the thrill of destruction without actually being in it."

As the planet downsizes itself, an ensemble struggles to survive. Woody Harrelson plays a nutcase conspiracy theorist; Danny Glover, in full gravitas mode, is the overwhelmed American president; and Chiwetel Ejiofor has the burden of explaining the bad news as the White House's chief science adviser.

Just like the ancient Maya myths said to predict the end of days in 2012, the governments of the world see the problem coming and have devised a fleet of arks to preserve the human species, as well as great works of art and favorite zoo animals.

"When you go to see a movie like this, it's giving voice to your worst fears. It's like running around on Halloween and celebrating ghouls and mayhem," Cusack says. "I don't know what it is in us, but we definitely want to come close to that edge. But if it were reality, we'd all be weeping all day."

Though Cusack is the lead, he shares top billing with the movie's other stars: city-dissolving earthquakes, volcanoes and continent-erasing floods.

"When you make a big visual effects or disaster movie, there's no bad guy," says Emmerich, who believes 2012 will be the last of his catastrophe films. "The bad guy's actually the disaster and you just have to survive it. I always thought that was interesting. When there is no bad guy, no bad guy can be killed."

Digital special effects create the images of California sliding into the Pacific, the crumbling Vatican steamrolling the faithful in St. Peter's Square, and a super volcano in Yellowstone National Park detonating a doughnut-hole in the continental United States. But for close-ups, the actors really were shaken, rattled and rolled on large-scale sets.

For instance, Cusack's rescue of his family from their collapsing neighborhood in Los Angeles took place on a residential block constructed on gimbals, so the street could split, palm trees could shudder and the fa?ade of houses could disintegrate as the heroes raced to safety.

Building it in the computer can be just as tough as making the set in real life, says Marc Weigert, visual effects supervisor and co-producer of the film. "Here we don't only have to create all the objects and make them look photo-realistic, but they have to be animated and falling apart," he says. "You need physics-based simulations of buildings crumbling, with dust, smoke, fire. ... Everything has to be created."

At a budget estimated at $200 million, Emmerich says, "it's the biggest movie I've made so far."

The other big effect is just old-fashioned imagination: directors cooking up new ways to destroy iconic monuments, actors reacting to unseen storms of debris, and background extras dying as tiny figures in a millisecond of wide-shot carnage.

But one climactic scene benefited from real-world inspiration. It was last Nov. 4, Election Day in the USA, recalls co-writer and producer Harald Kloser.

A crowd of about 100 people aboard the arks were celebrating their survival when an assistant director announced news of Barack Obama's victory.

Evidently, there were a lot of supporters. "Everybody broke out in cheers then, and the cameras were rolling," Kloser says. "So we had our cheer."

No disappointed John McCain supporters ruined the shot?

Kloser laughs: "It was quite a unanimous cheer."

Enlarge Columbia Pictures No bad guy: Jackson (John Cusack) is just trying to help his daughter (Morgan Lily) and son survive.