“Polyjuice Potion, Harry,” said Dumbledore. “You see the simplicity of it, and the brilliance. For Moody never does drink except from his hip flask, he’s well known for it. The imposter needed, of course, to keep the real Moody close by, so that he could continue making the potion. You see his hair . . . ” Dumbledore looked down on the Moody in the trunk. “The imposter has been cutting it off all year, see where it is uneven? But I think, in the excitement of tonight, our fake Moody might have forgotten to take it as frequently as he should have done . . . on the hour . . . every hour . . . We shall see.”

Dumbledore pulled out the chair at the desk and sat down upon it, his eyes fixed upon the unconscious Moody on the floor. Harry stared at him too. Minutes passed in silence . . .

Then, before Harry’s very eyes, the face of the man on the floor began to change. The scars were disappearing, the skin was becoming smooth; the mangled nose became whole and started to shrink. The long mane of grizzled gray hair was withdrawing into the scalp and turning the color of straw. Suddenly, with a loud clunk, the wooden leg fell away as a normal leg regrew in its place; next moment, the magical eyeball had popped out of the man’s face as a real eye replaced it; it rolled away across the floor and continued to swivel in every direction.

Harry saw a man lying before him, pale-skinned, slightly freckled, with a mop of fair hair. He knew who he was. He had seen him in Dumbledore’s Pensieve, had watched him being led away from court by the dementors, trying to convince Mr. Crouch that he was innocent . . . but he was lined around the eyes now and looked much older . . .

There were hurried footsteps outside in the corridor. Snape had returned with Winky at his heels. Professor McGonagall was right behind them.

“Crouch!” Snape said, stopping dead in the doorway. “Barty Crouch!”

“Good heavens,” said Professor McGonagall, stopping dead and staring down at the man on the floor.

Filthy, disheveled, Winky peered around Snape’s legs. Her mouth opened wide and she let out a piercing shriek.

“Master Barty, Master Barty, what is you doing here?”

She flung herself forward onto the young man’s chest.

“You is killed him! You is killed him! You is killed Master’s son!”

“He is simply Stunned, Winky,” said Dumbledore. “Step aside, please. Severus, you have the potion?”