What if we could heal our economic woes, reduce unemployment to less than 1 percent, and solidify America's position as the world's greatest financial and military power?

What if we could do it all in only a handful of years?

That's the utopian world offered in The Purge, a riveting, thoughtful psychological thriller starring Ethan Hawke (The Woman in the Fifth) and Lena Headey (Game of Thrones) which opens Friday.

The Purge is set in an America that has instituted a simple formula for achieving economic success: Cull the population once a year, cutting out (killing) the poor and the weak, the people who depend on our charity or on government handouts, the people who don't contribute anything to society.

That's the dark, politically loaded premise behind writer-director James DeMonaco's picture, a morality tale that tries to spook horror fans with real scares while mounting a virulent, if perhaps not always nuanced critique of America's culture of violence.

Set in the very near future, The Purge unfolds over an annual national holiday, established by the federal government, called the Purge. Once a year, for 12 hours, citizens can commit any crime without fear of reprisal. There are no cops, no ambulances, no firefighters during the Purge. Only angry mobs that hunt, capture, torture and kill whoever is unlucky enough not to live in a fortified house.

The film portrays a world that has given in to the most radical forms of social Darwinism and unregulated, unfettered capitalism. Where only the strong have a right to survive and the weak have no claim on our compassion.

The Purge has received mixed reviews. Some critics applaud its social critique, while others fault it for being clumsy and distracting. It was made through Jason Blum's Blumhouse Productions, a boutique firm that specializes in what Blum calls "low budget, high concept genre films," including Insidious and Sinister. Founded in 2000, the company hit the bigtime in 2007 with Paranormal Activity, which cost $15,000 to make and grossed $193 million worldwide.

"The Purge, more than any of our films, fits our paradigm," Blum said in a recent meeting in Center City. "It's a fun movie, it's exciting, thrilling . . . and I love that it smuggles a political message into a genre story."

DeMonaco said the film developed from a germ of an idea planted by his wife more than a decade ago.

"The idea came one day when my wife said an odd thing," he said in a recent phone interview. "We were in a road rage incident, and this guy who was really angry at us jumped out of his car." Incensed at the other driver and disturbed by his apparent rage, DeMonaco's wife said, "What if we all have a free one once a year?" What if we could kill one person a year without being arrested? DeMonaco said it seemed a great idea to explore the glorification of violence in American culture.

"Our relationship with crime in America and our relationship with violence seems so different from the rest of the world," he said. "We are under constant bombardment of violent images."

In the film, the Purge is credited with saving the country from social and economic collapse. It's a patriotic duty, the media proclaim, because it cleanses the nation of its parasites. It's also great therapy, helping people work through their repressed rage and jealousy by letting them express their darkest urges.

The film features Hawke and Headey as James and Mary Sandin, an affluent couple with two children. Their blind belief in the Purge is shattered when their son Charlie (Max Burkholder) helps a homeless African American war veteran (Edwin Hodge) elude a posse and hide at their house.

A creepy mob of psychotic prep school kids storm the Sandins' house, demanding they turn over the stranger or die with him. A moral dilemma unfolds for the Sandins: Help the man, or save themselves?

"I think good fiction tries to challenge the audience to think critically about their own society," said DeMonaco.

Well-paced, intensely claustrophobic and violent, The Purge sneaks its political message through the ubiquitous radio and TV news shows that act as a kind of wallpaper to the action.

In one report, an anchorman checks in on the murderous action around the country via live-camera "Purge feeds." In another, pundits debate the morality of the Purge.

DeMonaco, who first established himself in Hollywood as a screenwriter with two hits, The Negotiator and 2005's Assault on Precinct 13, said he was troubled by an apparent contradiction. In his words: "How do you criticize violence in a film that depicts violence, and at times makes the audience cheer it on?"

One answer is to focus on the consequences, to show how violence not only affects the victims but also leads to a kind of soul death in the perpetrator, he said. "I have to show the repercussions."