The door of the room burst open in a shower of red sparks and Harry wheeled around as Professor Lupin came hurtling into the room, his face bloodless, his wand raised and ready. His eyes flickered over Ron, lying on the floor, over Hermione, cowering next to the door, to Harry, standing there with his wand covering Black, and then to Black himself, crumpled and bleeding at Harry’s feet.

“Expelliarmus!” Lupin shouted.

Harry’s wand flew once more out of his hand; so did the two Hermione was holding. Lupin caught them all deftly, then moved into the room, staring at Black, who still had Crookshanks lying protectively across his chest.

Harry stood there, feeling suddenly empty. He hadn’t done it. His nerve had failed him. Black was going to be handed back to the dementors.

Then Lupin spoke, in a very tense voice.

“Where is he, Sirius?”

Harry looked quickly at Lupin. He didn’t understand what Lupin meant. Who was Lupin talking about? He turned to look at Black again.

Black’s face was quite expressionless. For a few seconds, he didn’t move at all. Then, very slowly, he raised his empty hand and pointed straight at Ron. Mystified, Harry glanced around at Ron, who looked bewildered.

“But then . . . ,” Lupin muttered, staring at Black so intently it seemed he was trying to read his mind, “ . . . why hasn’t he shown himself before now? Unless”—Lupin’s eyes suddenly widened, as though he was seeing something beyond Black, something none of the rest could see, “—unless he was the one . . . unless you switched . . . without telling me?”

Very slowly, his sunken gaze never leaving Lupin’s face, Black nodded.

“Professor,” Harry interrupted loudly, “what’s going on—?”

But he never finished the question, because what he saw made his voice die in his throat. Lupin was lowering his wand, gazing fixedly at Black. The Professor walked to Black’s side, seized his hand, pulled him to his feet so that Crookshanks fell to the floor, and embraced Black like a brother.

Harry felt as though the bottom had dropped out of his stomach.

“I DON’T BELIEVE IT!” Hermione screamed.

Lupin let go of Black and turned to her. She had raised herself off the floor and was pointing at Lupin, wild-eyed. “You—you—”

“Hermione—”

“—you and him!”

“Hermione, calm down—”

“I didn’t tell anyone!” Hermione shrieked. “I’ve been covering up for you—”

“Hermione, listen to me, please!” Lupin shouted. “I can explain—”

Harry could feel himself shaking, not with fear, but with a fresh wave of fury.

“I trusted you,” he shouted at Lupin, his voice wavering out of control, “and all the time you’ve been his friend!”

“You’re wrong,” said Lupin. “I haven’t been Sirius’s friend, but I am now—Let me explain . . . ”

“NO!” Hermione screamed. “Harry, don’t trust him, he’s been helping Black get into the castle, he wants you dead too—he’s a werewolf!”