Harry has a vision of Voldemort receiving the summons. Luna Stuns Alecto, knocking her out and waking the Ravenclaw students, who enter the common room. Amycus pounds on the door, but he’s too stupid to answer the doorknocker’s next question, and can’t get in. Harry slips into Voldemort’s mind and sees that Voldemort has decided to check on his locket Horcrux before coming to Hogwarts, giving Harry a little extra time.
Professor McGonagall arrives outside the room and lets Amycus in. Harry and Luna have recloaked, and Amycus sees only his Stunned sister on the floor. His chief worry is that they will be punished for giving a false alarm, and he muses aloud that he can blame the summons on the Ravenclaw students, so Voldemort may be satisfied with killing a few of them. When Professor McGonagall stands up to Amycus defiantly, he spits in her face, prompting Harry to step out of the Cloak and deliver a Cruciatus Curse at Amycus.
Professor McGonagall urges Harry to flee, but when he explains that he is looking for the lost diadem of Ravenclaw on Dumbledore’s orders, she says that the teachers will secure the school from Voldemort while he searches. Visions of Voldemort reveal to Harry that Voldemort has discovered that his locket is missing and is on his way to the school.
Harry and Professor McGonagall quickly make a plan to alert the other heads of houses and evacuate any students unwilling or too young to fight against Voldemort. They are on their way to alert the heads, with Harry and Luna hidden under the cloak, when they meet Severus Snape in the hallway. When Snape demands to know if McGonagall has seen Harry Potter, she attacks him, and they duel. McGonagall holds Snape at bay, and he is finally forced to take flight when Professors Sprout and Flitwick run up to aid her. Snape leaps from the window and flies away on huge, batlike wings.
Professor McGonagall organizes the other professors in establishing magical defenses and evacuating students, putting to work those students who can help defend the school, including Dumbledore’s Army. Lupin and the entire Weasley family enter the school in order to help, with Percy apologizing for being a pro-Ministry prig and Lupin showing pictures of his and Tonks’s baby.
Ginny Weasley tells Harry that Ron and Hermione said something about heading to a bathroom. Harry starts to look for them when he has a vision of Voldemort arriving at the school gates, Nagini draped across his shoulders.