"Did you hear that?"

Harry froze, and Ron and Hermione walked into him. They didn't seem to notice; they were too busy bickering furiously under their breaths, barely aware that they'd all come to a stop beneath Harry's invisibility cloak.

"… think you broke my foot, Ron!"

"… can't help it if the cloak isn't big enough this year…"

"… at least try to be graceful and take smaller steps…"

"… stop clinging on to my robes, it's not that dark out…"

"… I was not clinging!"

"Shut up!" Harry hissed, and his companions' mouths snapped shut. They both turned to glare at him, but Harry didn't care. The corridor was now completely silent. Harry stood absolutely still and strained his ears. The halls of Hogwarts in the middle of the night were usually silent and still, save for the occasional flickering flames of the torches on the walls. Harry frowned. He was sure he'd heard…

CRASH!

"Bloody hell!" Ron swore, jumping a foot. The three of them pivoted, with some difficulty, beneath the cloak, and turned to look back down the corridor, behind them.

"Come on," Harry muttered, and set off quickly, the other two struggling to keep up with him and stay hidden beneath the cloak.

"Do you think someone is hurt?" Hermione asked anxiously, nearly jogging to keep up.

Harry didn't answer as they turned a corner, Ron skidding so that a pair of disembodied, gangly legs appeared flailing out of nowhere. Luckily, there was no one around to notice.

There was another cringe-worthy crash, and a sound that made the hair on Harry's neck stand up… an animal howling…

"It's coming from Professor Lupin's office!" Harry shouted as they rounded a corner and ended up in front of a closed door. Inside, they could hear furniture breaking, glass shattering, and something big moving around…

Harry grabbed the handle and tugged. The door was locked tight.

"Harry, wait!" Hermione gasped.

A man's voice cried out from inside.

"Professor!" Ron shouted, banging on the door.

"Oh no… stand back! Alohomora!" Hermione cried, waving her wand at the handle.

The door sprang open, and Harry hurried inside. He skidded to a halt.

Professor Lupin's office was completely trashed. Furniture had been overturned, table and chair legs ripped from their bases. Paper was scattered all over the room, bits of it burning from spilt and toppled candles. The curtains were torn and ripped from where they hung on the window. The grindylow cage was smashed and empty.

A thin, ragged, balding man stood in the middle of it all, his robes askew, clutching a wand and pointing it shakily at a huge, black mass in the shadowy corner of the room. It took a moment for Harry's eye to adjust, and then his stomach plummeted when the black mass came into focus.

It was a werewolf.

Ron yelped and whipped out his wand, thrusting to toward the werewolf. "Oh bloody…"

"No, don't Ron!" Hermione gasped, grabbing his arm. "That's Professor Lupin!"

"That thing ate Professor…?!"

"No, that thing is Professor Lupin!"

For a moment, everyone stood frozen. The thin, balding man was gasping for breath, his wand trembling violently in his hand as he pointed it at the dark, hulking creature in the corner. Ron's mouth was wide open in terror. Harry's heart was thudding in his ears.

Then the creature let out a terrible moan, and shifted slightly. For the briefest moment, its eyes met Harry's.

The balding man made a sudden movement. "Avada Ked –"

"Relashio!" Hermione screamed.

The balding man stumbled back, yelping, clutching his wand-hand which had been hit by Hermione's spell. Harry saw one of his hands had a finger missing.

"He's trying to kill Lupin!" Hermione cried.

The balding man, who had caught himself from falling by grabbing onto the back of a chair, aimed his wand at Hermione and screeched, "Stupify!"

There was a terrible CRACK and Hermione was thrown backward, falling over an overturned bookcase and landing in a heap on the ground.

"Hermione!" Harry and Ron bellowed.

Harry spun to face the balding man, who had turned one last time to the werewolf in the corner. The man pointed his badly shaking wand at the werewolf, and Harry took up where Hermione left off and unthinkingly lunged at the man just as he cried, "Confringo!"

Harry crashed into the man, knocking them both off their feet; the spell missed the wolf and hit above it, and the room rocked with explosion. Blinded, deafened, and choking on smoke and dust, Harry felt himself land hard on the man's wand arm, felt them both crash into the wall, felt jars crash down on them, soaking them in escaped liquids.

Quite suddenly, the man's arm disappeared from beneath Harry, and as Harry scrambled to get his bearing, he realized the man was gone.

"Ron!" Harry shouted, hearing his own voice sound quite muffled behind a vicious ringing in his head. "Hermione!"

"Harry!" He heard Ron shout as if from far away.

Harry felt around him, squinting through the dust. There was a bright flickering against one side of the room… fire!

"Where is he?" Harry asked, feeling around him, trying to discern through the dirty air. "He's gone!"

Harry found his own wand on the ground beside the wand the man seemed to have dropped. Grabbing both, Harry shakily got to his feet, his side stabbing with pain where he'd hit the corner of Lupin's trunk, and he stumbled over the Ron and Hermione, who, Harry saw with immense relief, was awake and alert, Ron kneeling next to her, his wand held tightly in his fist as if waiting to be attacked again.

"Harry!" she gasped. "Are you hurt?" A trickle of blood ran down from her hairline.

"I'm fine, what about you?"

Hermione, who was breathing hard, reached down the front of her robes and pulled out a long chain. "Oh no…" she muttered, staring at it in horror.

"He got away!" Ron exclaimed as the smoke and dust began to settle. "Harry… he got away!"

There was another whimpering moan, and the three of them turned to see the wolf barely stirring beneath a wardrobe that was now a raging inferno.

"Ron, get help!" Hermione gasped, grabbing the front of his robes. "Get Professor Dumbledore, hurry!"

"We all have to get out of here… that's a werewolf!" Ron got to his feet, one hand gripping Hermione's arm as he tried to pull her up, too.

"We have to help him!" Hermione cried, and Harry ran forward toward the creature in the corner. It appeared to be dead. Professor Lupin or not, Harry didn't want to see it burn to death. Pocketing both wands, he reached out and grabbed the beast by the scruff of its neck and by one of its front legs, and dragged it with immense difficulty away from the blazing curtains above it.

"Are you mad!" Ron bellowed, but a moment later he was at Harry's side, pulling the limp werewolf away from the fire to the middle of the room.

Harry turned, sweating, gasping, coughing on the smoke that was quickly filling up the room. Hermione was leaning against the wall, watching them with fear.

Footsteps filled the corridor outside, and suddenly Filch, Snape, McGonagall, Hagrid, and Dumbledore were all standing in the hall, staring in shock into Professor Lupin's burning office while a dirty, sooty, sweaty Harry, Ron, and Hermione stared back, an unmoving werewolf at their feet.