“Are you insane?” said Harry, his voice easily as croaky as Black’s. “Of course I want to leave the Dursleys! Have you got a house? When can I move in?”

Black turned right around to look at him; Snape’s head was scraping the ceiling but Black didn’t seem to care.

“You want to?” he said. “You mean it?”

“Yeah, I mean it!” said Harry.

Black’s gaunt face broke into the first true smile Harry had seen upon it. The difference it made was startling, as though a person ten years younger were shining through the starved mask; for a moment, he was recognizable as the man who had laughed at Harry’s parents’ wedding.

They did not speak again until they had reached the end of the tunnel. Crookshanks darted up first; he had evidently pressed his paw to the knot on the trunk, because Lupin, Pettigrew, and Ron clambered upward without any sound of savaging branches.

Black saw Snape up through the hole, then stood back for Harry and Hermione to pass. At last, all of them were out.

The grounds were very dark now; the only light came from the distant windows of the castle. Without a word, they set off. Pettigrew was still wheezing and occasionally whimpering. Harry’s mind was buzzing. He was going to leave the Dursleys. He was going to live with Sirius Black, his parents’ best friend . . . He felt dazed . . . What would happen when he told the Dursleys he was going to live with the convict they’d seen on television . . . !

“One wrong move, Peter,” said Lupin threateningly ahead. His wand was still pointed sideways at Pettigrew’s chest.

Silently they tramped through the grounds, the castle lights growing slowly larger. Snape was still drifting weirdly ahead of Black, his chin bumping on his chest. And then—

A cloud shifted. There were suddenly dim shadows on the ground. Their party was bathed in moonlight.

Snape collided with Lupin, Pettigrew, and Ron, who had stopped abruptly. Black froze. He flung out one arm to make Harry and Hermione stop.

Harry could see Lupin’s silhouette. He had gone rigid. Then his limbs began to shake.

“Oh, my—” Hermione gasped. “He didn’t take his potion tonight! He’s not safe!”

“Run,” Black whispered. “Run. Now.”

But Harry couldn’t run. Ron was chained to Pettigrew and Lupin. He leapt forward but Black caught him around the chest and threw him back.

“Leave it to me—RUN!”

There was a terrible snarling noise. Lupin’s head was lengthening. So was his body. His shoulders were hunching. Hair was sprouting visibly on his face and hands, which were curling into clawed paws. Crookshanks’s hair was on end again; he was backing away—