Nightmare Academy (Veritas Project #2) by Frank Peretti

The Veritas Project team has a new assignment: To find the truth behind the mysterious disappearance of two runaways. When one runaway turns up totally out of his mind, and a government agent steps in to take over the case, the Springfields continue their own investigation. The twins, Elijah and Elisha, go undercover, posing as runaways. What happens next will keep readers on the edges of their seats as the twins end up in a strange academy where Truth is challenged, a gang-like war develops, and Elijah is taken to an ominous mansion from which no one has ever returned. A great thriller with a realistic look at right and wrong.