Under the Invisibility Cloak, Harry, Ron, and Hermione follow Draco to Borgin and Burkes, a dark magic shop in Knockturn Alley. Draco threatens Mr. Borgin about repairing one item and keeping another safe for him. Draco shows Mr. Borgin something on his arm that Harry believes to be the Dark Mark, Voldemort's sign, though whether or not Harry is correct is never confirmed. (In the film version Draco Malfoy shows Dumbledore the Dark Mark on his arm.) On the Hogwarts Express, Harry invisibly spies on Draco and overhears him discussing Voldemort's task with several other Slytherins. Draco knows Harry is present and, once alone in the compartment, immobilises him and breaks his nose causing Harry to hate Draco even more. Harry is left stranded on the train until Nymphadora Tonks (Luna Lovegood in the film adaptation) rescues him. Harry spends much of the year trailing Draco's whereabouts on his Marauder's Map, but loses track of him once Draco enters the Room of Requirement. When Katie Bell is almost killed in Hogsmeade after handling a cursed necklace and Ron nearly dies by drinking poisoned mead, Harry suspects Draco is behind both attacks.