Hangman's Curse by Frank E. Peretti

They could be anyone, anywhere . . . even the person walking by you right now.

The Veritas Project is their code name—but only a handful of people know teens Elijah and Elisha Springfield have been covertly commissioned by the President to investigate strange mysteries that delve into the paranormal and supernatural. Their charge is to find out not only what happened, but why—the veritas (Latin for truth) behind the seemingly impossible phenomena.

Their new assignment: Hangman's Curse

In Baker, Washington, three popular student athletes lie in an incoherent coma, with loss of muscle coordination, severe paranoia, and hallucinations. It's whispered that they're victims of Abel Frye—a curse that's haunted the school since a student died there in the 1930s. Now the curse is spreading, and students are running scared. The Veritas Project must go undercover to find the truth . . . before it's too late.