It plays out like a video war game on steroids.
Jolts to the user's floorboard accentuate the sensations of combat in a war-torn city.
Research assistant Brady Helds reacted physically when testing the system.
"My hands definitely began sweating when the combat kicked in," he says.
His eye mask lets him check for trouble in every direction.
"It was loud and intense. I wanted to get out of that area," he recalls.
The digital nightmare is no game. It is a deadly serious effort to help U.S. soldiers and rescue workers cope with PTSD.
"We teach them how to understand what's going on in their body," explains Skip Rizzo of the USC Institute for Creative Technologies.
The program was dreamed up by the U.S. military and Hollywood special effects artists, with the help of two pioneering psychologists...Rizzo and Galen Buckwalter of Pasadena's Headington Institute, a counseling center for civilian first responders.
Part of the program is a repair effort, to help the victims of post-traumatic stress get over it by putting them back into terrifying situations, only this time through virtual reality so they can control their emotions in a safe environment.
"We teach them tactics to help them to manage stress like deep breathing or thought focusing exercises," Rizzo explains.
The program also is designed to prevent trauma.
Military personnel and first responders get a virtual taste of the terrors that await them, and learn the ways to cope.
Dr. Buckwalter says a sense of purpose and pride in the mission can actually temper the body chemistry of potential victims as they head into dangerous situations.
"So they can control the tendency to let their hormones go out of control," he explains.
If the research proves out, U.S. troops going off to war, or coming home from it, may eventually be better equipped to defeat the enemy that threatens them from within.
Virtual reality is being used as therapy for PTSD at 20 military treatment centers nationwide.
After four years of clinical use, researchers caution that technology alone can't do the job.
It takes trained psychologists working with patients to maximize the effects of this unusual treatment program.