Harry demands to know where Sirius is. Malfoy asks Harry to give him the prophecy, but Harry refuses to relinquish the sphere, threatening to smash it if the encroaching crowd of Death Eaters attack his friends. Malfoy tells him the sphere contains the story of his scar and explains that only those about whom a prophecy has been made can safely retrieve it. Voldemort could not come himself because the Aurors at the Ministry would have caught him immediately, so they lured Harry here by manipulating his dreams and making him think Sirius was in trouble.
At Harry’s signal, the students use their wands to shatter the rows of spheres. Harry sprints from the chamber, gripping his prophecy. The Death Eaters follow. Hermione is stunned by a Death Eater and falls to the ground. Neville’s nose is broken in the fray. Ron falls under some sort of lunacy spell, and Ginny’s ankle is broken by a Death Eater. Dragging Hermione, they keep moving, but five Death Eaters corner them in the brain room. The brain jar bursts open, and Ron picks one up. Tentacles shoot out and try to strangle Ron. Death Eaters stun Ginny and toss Luna into a desk. Both lie unconscious, leaving only Neville and Harry to fight the remaining Death Eaters. Harry, still clutching the prophecy, runs into the room with the arch. Neville follows, and Lestrange begins to torture Neville with the Crucio curse.
Suddenly, Sirius, Lupin, Moody, Tonks, and Kingsley appear. Sirius yells for Harry to take Neville and the prophecy and run. As Harry attempts to grab Neville, the prophecy slips from his robes and cracks open. Dumbledore appears and corrals the Death Eaters. Lestrange, dueling with Sirius, sends a jet of red light right into his chest, and he falls through the curtains. Harry runs to the arch, but Lupin holds him back. Lupin tells Harry that Sirius is gone.
Harry refuses to believe that Sirius is dead. He spots Lestrange and runs after her, vowing to avenge Sirius’s murder. He catches up to her in the Atrium. Harry shouts at Lestrange that the prophecy is gone and that she will have to kill him. Voldemort and Dumbledore appear. Voldemort strikes Dumbledore, but Dumbledore’s bird, Fawkes, takes the blow. Voldemort disappears, and Harry’s scar bursts open. Voldemort uses Harry’s voice to speak to Dumbledore, asking Dumbledore to kill him by killing Harry. Suddenly, Harry feels Voldemort leave his body, and he crumples to the floor. Harry learns that Voldemort had grabbed Lestrange and Disapparated from the Ministry. Cornelius Fudge runs in, confused. He demands to know what has happened, and Dumbledore promises to tell him after he sends Harry back to Hogwarts. Still stunned, Dumbledore gives Harry a Portkey and Harry whizzes back to Dumbledore’s office.
Dumbledore meets Harry in his office. Harry is visibly upset about Sirius’s death. Dumbledore tells Harry this pain is his greatest strength. Dumbledore admits it’s his own fault that Sirius is dead because he never told Harry the whole truth about his scar. Dumbledore explains. On the night Harry saw Mr. Weasley attacked, Voldemort figured out that Harry’s scar allowed Harry to be privy to Voldemort’s thoughts and actions. Assuming this connection must work both ways, Voldemort began forcing his way into Harry’s thoughts, which is why Dumbledore ordered Snape to give Harry Occlumency lessons. Voldemort knew the only person Harry would go to great lengths to save was Sirius, so he projected the image of Sirius’s torture into Harry’s mind. Voldemort needed Harry to retrieve the prophecy because he could not risk entering the Ministry himself, and no one else would ever be able to touch it.
When Harry was an infant, Hagrid took him to the Dursleys instead of a Wizarding family because, in order to remain safe, Harry needed to be near his mother’s blood, which came in the form of Aunt Petunia. As long as Harry can still call the place where his mother’s blood dwells home, he is safe. Dumbledore sent the Howler to Petunia to remind her of this bond.