Scavenger Hunt (Vintage Paperback) by Christopher Pike

School was almost over. A secretive club on campus had organized a scavenger hunt for the entire senior class. In small groups, and with the help of cleverly planted clues, the kids are led throughout the city, and then deep into a nighttime desert. The sponsoring club has promised a wonderful prize for the first group to reach the goal of the hunt. But for Carl Timmons, a troubled young man who has recently lost his best friend, the hunt will become a nightmare. Led astray by his love for a strangely beautiful girl, he will wander far from the others, and back into a haunted past, where the line between hte living and the dead is blurred and broken.