Teenagers spend the night in an abandoned mall where they're stalked by a trio of escaped psychopaths wearing Santa Claus masks.

SYNOPSIS:

Three psychotic patients murder their nurses and flee the sanitarium - the imposing, barrel-chested Ronnie, lanky oddball Lonnie and minuscule but menacing Donnie.

A car chase ensues with law enforcement on their tail. Driving their stolen vehicle, Ronnie takes a sharp turn, sending the car off a cliff. Leading law enforcement on the scene is Sheriff Jason Hershey. The car has been totaled but, to Sheriff Hershey's amazement, no bodies have been recovered.

Donnie, Lonnie and Ronnie managed to escape the vehicle, taking off on foot. Battered and bruised but determined to survive, they continue on and, at sunrise, arrive at their destination – the abandoned Hooper Park Mall.

Across town the next morning, teenager Ryan Wilson watches an old TV commercial for Hooper Park Mall on his phone. Ryan is hooked on online mall explorer videos in which trespassers record their journeys into rotting retailers. Demolition on Hooper Park Mall, which has sat dormant for more than a decade, is scheduled for the next day – and Ryan is determined to venture inside before it's gone for good.

It's an idea hardly embraced by his closest friends, Jack and Hannah. But when Ryan declares he'll break into the mall by himself that night, his pals relent and agree to join him for support.

That afternoon, the escapees break into Betty's Costume Boutique, a shop inside the mall that inexplicably sports products left behind from long ago. They rummage through old boxes, digging until they find a collection of Santa Claus masks. Excited by their findings, they put the masks on.

As dusk falls, the teens enter the mall. Inside, it's the most haunting and mesmerizing of sights, just as Ryan imagined. One empty storefront after another. Graffiti, shattered glass and toys scattered all over.

The food court and movie theater, once the most hopping mall spots of all, are now eerie relics. Elsewhere in town, Sheriff Hershey has teamed up with Dr. Adrienne Hill, the escapees' former psychiatrist, in search of the escapees.

Eventually, a demented game of tag among the escapees leads to a confrontation with the teens. The escapees chase after the teens, who barricade themselves inside the movie theater. All emergency exits have been bolted shut.

Jack, fearful of being kicked off the football team if their trespassing is discovered, convinces Ryan and Hannah not to call the police. Instead, Ryan calls on his older sister Abbey to come to the rescue.

Abbey, alongside boyfriend Blake and friends Tyler and Madison, venture to the mall and split up. Donnie and Lonnie, now sporting weapons stolen from the mall security office, murder Tyler and Madison.

Discovering their corpses upon arrival at the mall are Dr. Hill and Sheriff Hershey, who immediately calls for backup. A violent tussle soon, however, ensues among them and Donnie and Lonnie that leaves Sheriff Hershey dead and Dr. Hill severely injured.

Outside the movie theater, Abbey and Blake find themselves surrounded by all three escapees. On the verge of being their latest victims, they score a reprieve from the teens, emerging from the theater. Jack kills Lonnie with a movie projector, while Ryan stabs Donnie to death. A gruesome fight erupts between Ronnie and Blake that leaves the latter decapitated.

Ryan is nearly struggled to death by Ronnie until Dr. Hill emerges from nowhere and shoots Ronnie down an escalator.

Finally but far too late, police arrive on the scene. Outside the mall, the survivors watch as six body bags are brought out – one short of the total number of victims. Ronnie's body was not recovered.

One year later, Ryan is at home in bed, chatting on the phone with Hannah, who he's now dating. He goes to the bathroom and, upon returning to the bedroom, finds the window curiously open. He shuts it and hits the sack but is unable to sleep, transfixed by something he thinks he sees in the closet. Ryan gets up and opens the door to check it out. There's nothing.

Awaiting him on the other side of the door is Ronnie.