Professor Terence Scott travels to River Heights to consult with Carson Drew about the disappearance of another professor, Dr. Joshua Pitt. Mr. Drew recommends he discuss the matter with Nancy, as it seems to be more of a mystery than a legal matter. Terry Scott reveals that while on an archaeology expedition in Mexico, he, Dr. Pitt, and two other professors, Dr. Anderson and Dr. Graham, found a clue to an ancient treasure. They discovered three black keys made of obsidian and a stone tablet with a cipher engraved on it. The items and Dr. Pitt both disappeared the next morning. Only a broken half of one of the keys was left behind. Terry suspected foul play by a couple who had been working near the excavation site because they vanished at the same time.
