Hermione was certain that the male Slytherin sixth-year prefect, Tom Riddle, was up to no good. Lately he had been spending a lot of time in the Restricted Section of the Hogwarts library, but he had been coming away from it with scowls of discontent on his face. Then there was that Slug Club meeting earlier this year. She had left the meeting punctually, but she had heard the Slytherin boys laughing with Professor Slughorn for some time afterward—and then Riddle himself had stayed behind for a one-on-one talk with the professor about something. Hermione had lurked in the hall under a perfect Disillusionment Charm, ear pressed against the door to try to hear what they were saying, but she only caught bits of it. Slughorn had looked extremely disturbed when the private talk was over, however, and Riddle had looked ecstatic—but not in a good way. Whatever Riddle was seeking information about, Hermione was sure that it was Dark.