My mind had gone blank with shock as I let a whimper. The four of us stood transfixed with horror under the Invisibility Cloak. The very last rays of the setting sun were casting a bloody light over the long-shadowed grounds. Then, behind us, we heard a wild howling, breaking my heart even more.

"Hagrid," Harry muttered.

He made to turn back, but both Ron and Hermione seized his arms.

"We can't," Ron said, who was paper-white. "He'll be in worse trouble if they know we've been to see him..."

Hermione's breathing was shallow and uneven.

"How-could-they?" she choked. "How could they?"

We set off back toward the castle, walking slowly to keep ourselves hidden under the cloak. The light was fading fast now. By the time we reached the open ground, darkness was settling like a spell around them.

"Scabbers, keep still," Ron hissed, clamping his hand over his chest. The rat was wriggling madly. Ron came to a sudden halt, trying to force Scabbers deeper into his pocket. "What's the matter with you, you stupid rat? Stay still- OUCH! He bit me!"

"Ron, be quiet!" Hermione whispered urgently. "Fudge'll be out here in a minute-"

"He won't-stay-put-"

Scabbers was plainly terrified. He was writhing with all his might, trying to break free of Ron's grip.

"What the matter with him?"

That's when I noticed slinking toward us, his body low to the ground, wide yellow eyes glinting eerily in the darkness-Crookshanks. Whether he could see us or was following the sound of Scabbers's squeaks, I couldn't tell.

"Crookshanks!" Hermione moaned. "No, go away, Crookshanks! Go away!"

But the cat was getting nearer-

"Scabbers-NO!"

Too late-the rat had slipped out of Ron's clutching fingers, hit the ground, and scampered away. In one bound, Crookshanks sprang after him, and before any of us could stop him, Ron had thrown the Invisibility Cloak off himself and pelted away into the darkness.

"Ron!" Hermione moaned.

She and Harry looked at me as if they were asking me to help, making me sigh and followed at a sprint; it was impossible to run fully under the cloak; we pulled it off and it streamed behind us like a banner as we hurtled after Ron; we could hear his feet thundering along ahead and his shouts at Crookshanks.

"Get away from him-get away-Scabbers, come here-"

There was a loud thud.

"Gotcha! Get off, you stinking cat-"

The three of us almost fell over Ron; we skidded to a stop right in front of him. He was sprawled on the ground, but Scabbers was back in his pocket; he had both his hands tight over the quivering lump.

"Ron-come on-back under the cloak-" Hermione panted. "Dumbledore-the Minister-they'll be coming back out in a minute-"

But before we could cover ourselves again, before we could even catch our breath, we heard the soft pounding of gigantic paws...Something was bounding toward us, quiet as a shadow-an enormous, pale-eyed, jet-black dog.

I watched as Harry reached for his want, but too late-the dog had made an enormous leap and the front paws hit him on the chest; he keeled over backwards in a whirl of hair, but the force of its leap had carried it too far; it rolled off him. Harry tried to stand up as it growled ready for a new attack.

Ron was on his feet. As the dog sprang back toward us he pushed Harry aside; the dog's jaw fastened instead around Ron's outstretched arm. Harry lunged forward, he seized a handful of the brute's hair, but it was dragging Ron away as easily as though he were a rag doll-

Then, out of nowhere, something hit me so hard across the face I was knocked off my feet. I heard Hermione and Harry shriek with pain and fall too.

I groped for my wand, blinking blood out of my eyes-

"Lumos!" I whispered.

The wandlight showed me the trunk of a thick tree; we had chased Scabbers into the shadow of the Whomping Willow and its branches were cracking as though in high wind, whipping backwards and forward to stop us going nearer.

And there, at the base of the truck, was the dog, dragging Ron backward into a large gap in the roots-Ron was fighting furiously, but his head and torso were slipping out of sight-

"Ron!" Harry shouted, trying to follow, but a heavy branch whipped lethally through the air and he was forced backward again; he was bleeding from his head too.

All we could see now was one of Ron's leg which he had hooked around a root in an effort to stop the dog from pulling him farther underground-but a horrible crack cut the air like a gunshot; Ron's leg had broken, and a moment later, his foot vanished from sight.

"Harry-we've got to go for help-" Hermione gasped; she was bleeding too; the Willow had cut her across the shoulder.

"No! That thing's big enough to eat him; we haven't got time-"

"Harry-we're never going to get through without help-"

"If that dog can get in, we can too," I panted, darting here and there Harry following me, trying to find a way through the vicious, swishing branches, but we couldn't get an inch nearer to the tree roots without being in range of the tree's blows.

"Oh, help, help," Hermione whispered frantically, dancing uncertainly on the spot, "please..."

Crookshanks darted forward. He slithered between the battering branches like a snake and placed his front paws upon a knot on the trunk.

Abruptly, as though the tree had been turned to marble, it stopped moving. Not a leaf twitched or shook.

"Crookshanks!" Hermione whispered uncertainly. She now grasped Harry's arm. "How did he know-?"

"He's friends with that dog," Harry said grimly. "I've seen them together. Come on-and keep your wands out-"

We covered the distance to the trunk in seconds, but before we had reached the gap in the roots, Crookshanks had slid into it with a flick of his bottlebrush tail. Harry went first and then I went; I crawled forward, headfirst, and slid down an earthy slope to the bottom of a very low tunnel. Crookshanks was a little way along, his eyes flashing in the light from Harry's wand. Second laters, Hermione slithered down beside him.

"Where's Ron?" she whispered in a terrified voice.

"This way," Harry said, setting off, bent-backed, after Crookshanks.

"Where does this tunnel come out?" Hermione asked breathlessly from behind me.

"I don't know...It's marked on the Marauder's Map but Fred and George said no one's ever gotten into it...It goes off the edge of the map, but it looked like it was heading for Hogsmeade..."

Marauder's Map? I wanted to ask what it was but it didn't feel right to ask them anything. It didn't feel right coming along with them. But I had to.

We moved as fast as we could, bent almost double; ahead of us, Crookshanks's tail bobbed in and out of view. On and on went the passage; it felt like we had been in there for a long time but then the tunnel began to rise; moments later it twisted, and Crookshanks had gone. Instead, we could see a patch of dim light through a small opening.

The three of us paused, gasping for breath, edging forward. Wand raised to see what lay beyond.

It was a room, very disordered, dusty room. Paper was peeling from the walls; there were stains all over the floor; every piece of furniture was broken as though somebody had smashed it. The windows were all boarded up.

Harry glanced at Hermione, who looked very frightened but nodded, then he glanced at me, sacred but not showing it, I nod.

Harry pulled himself out of the hole, staring around. The room was deserted, but a door to our right stood open, leading to a shadowy hallway. Hermione suddenly grabbed my arm. Her wide eyes were traveling around the boarded windows.

"Guys," she whispered as I slid my arm out of her grip. "I think we're in the Shrieking Shack."

I looked around. My eyes fell on a wooden chair near us. Large chunks had been torn out of it; one of the legs had been ripped off entirely.

"Ghosts didn't do that," I said slowly.

At that moment, there was a creak overhead. Something had moved upstairs. The three of us looked up at the ceiling. Without a second thought, I move forward out into the hall and up. I wasn't going to let my fear stop me from saving Ron.

Everything was covered in a thick layer of dust except the floor, where a wide shiny stripe had been made by something being dragged upstairs.

We reached the dark landing.

"Nox," we whispered together, and the lights at the end of our wands went out. Only one door was open. As we crept toward it, we heard movement from behind it; a low moan, and then a deep, loud purring. We exchanged a last look, a last nod.

Wand held tightly before me, I kicked the door wide open.

On a magnificent four-poster bed with dusty hangings lay Crookshanks, purring loudly at the sight of us. On the floor beside him, clutching his leg, which stuck out at a strange angle, was Ron.

We all hashed across to him.

"Ron-are you okay?"

"Where's the dog?"

"Not a dog," Ron moaned. His teeth were gritted with pain. "Harry, it's a trap-"

"What-"

"He's the dog...he's an Animagus..."

Ron was staring over Harry's shoulder. We all wheeled around. With a snap, the man in the shadows closed the door behind us.

A mass of filthy, matted hair hung to his elbows that I once saw earlier today. If eyes hadn't been shining out of the deep, dark sockets, he might have been a corpse. The waxy skin was stretched so tightly over the bones of his face, it looked like a skull. His yellow teeth were bared in a grin.

It was Sirius Black.