A "cyber-terrorist" threatens Plainfield, Indiana during and after Christmas break 2015. He goes by the scary name of "Brian Kil."

On a Facebook posting he promises to unleash a violent bloodbath on students at Plainfield High School.

"The time is nearly here. I am shaking with excitement. I want to leave a trail of death and fire at Plainfield," "Kil" wrote.

Various students are tagged in the post, allowing them to read it and spread the word. The cyber-suspect promises all-out carnage, using handguns, pipe bombs and an assault rifle as weapons of mass destruction.

The community panics, and police immediately shut down Plainfield High School and nearby Danville High School the following day as a precaution.

But the mysterious poster is just revving up, leveling similar apocalyptic threats at a local mall, forcing the evacuation of stores and the movie theater in the middle of the holiday rush.

Though the FBI is called in to help, tracking down the online perpetrator is next to impossible due to the complexities of Internet technology.

"Doing an investigation like this is a very complicated thing," said cyber expert Peter Beering. "The Internet is a series of connected servers and routers, and it's called 'the Web' because it literally is a web."

Brian Kil's reign of terror escalates during the school's winter break, his deadly vows becoming increasingly graphic and depraved, promising parents to "laugh as your kids pound and claw at the windows in a last attempt to find an exit."

Meanwhile, the ongoing cyber-investigation finally begins to turn up suspects. A nighttime raid of several homes results in confiscated computers and hard drives, plus surprise police interrogations. The teen suspects were questioned and released.

Understandably, the fear factor among Plainfield parents skyrockets. But a community meeting to dial down the anxiety has just the opposite effect when one man suddenly jumps to his feet.

Ronald Kendall, 37, is arrested and charged with possession of a firearm on school property after he alerted the crowd that he had a gun in his coat pocket. His trial is scheduled for April.

Though there's speculation he was making a point about the ease of sneaking weapons onto campus, the incident does nothing to soothe frazzled nerves.

So far no one has been charged with the threats. But with the town consumed by fear, one crucial question remains: Who is Brian Kil? Is he a disturbed student? A sick prankster? A psychopath? Or maybe even someone outside the United States?

Whoever Brian Kil is, officials are making their own threat, one they say is a promise.

"Likely, we're going to be able to attribute identity, find out who you are and locate you," said Indiana State Police Captain Chuck Cohen.