He was gone almost before James realized it. The curtain at the back of the storage room still swayed where the man had blown through it. To James' great surprise, he darted to follow the man.
The Potions storage room led into the Potions classroom itself. Long, high tables stood in the darkness, their stools tucked neatly beneath them. James stopped and cocked his head. Footsteps echoed from the corridor beyond. His own feet smacked the stone floor as James dodged around the tables and out into the corridor, following the man.
The man was hesitating at a point where two corridors crossed. He looked desperately back and forth, then glanced up and saw James coming. The man let out the same high, little shriek James had heard him make when he'd been chased by the ghost. He slipped on the stones, his feet seeming to run in three directions at once, then he mastered them and ran clumsily down the broader corridor. James knew where he was now. The man would come out onto the hall of the moving staircases. Even as James was thinking it, he heard another little shriek of surprise echoing back to him. He grinned as he ran.
James stuttered to a stop at a railing and leaned over, peering intently into the darkness of the floors below. At first, the subtle grinding of the stairs was the only noise, and then he heard the clatter of the man's shoes. There he was, holding onto a railing for dear life and stumbling down a staircase as it swiveled ponderously. James hesitated for a moment, then did something that he'd always wanted to do but never quite had the temerity to try: he clambered up on the railing of the nearest staircase, straddled it, and then let go.
The thick wooden railings, polished by generations of house-elves to a rocklike, glassy shine, were like beams of ice beneath James. He shot down the railing, craning his head over his shoulder to see where he was going. His hair, which had gotten lank with sweat in the minutes before, ruffled as air whipped past. When he neared the bottom, he gripped the railing again with both his arms and his legs, slowing, and then hopping lightly off the bottom. He cast around, looking for the man, and saw him clambering toward another landing, one floor below.
James' dad had told him about the moving staircases, had explained the secret of navigating them. James gauged the moving labyrinth, and then chose another staircase just as it began to swivel. He swung himself over the railing and let go, streaking down it as if it were greased. On one side was the swaying chasm of landings, staircases, and halls; on the other, the speed of the blurring stairs. James gritted his teeth and craned to look behind him again. The man was just reaching the landing below. He stumbled, disoriented, as he backed off the staircase, and then looked up just as James rocketed into him.
James hit the man at full speed, rebounded off him, and sprawled onto the flagstones of the landing. The man shrieked a third time, this time in frustration and surprise, as the force of the collision knocked him entirely off his feet. There was a piercingly loud crash, followed by a shower of tinkling glass. James rolled and covered his face instinctively. When silence descended again, James peeked through his fingers. There was a very large, roughly man-shaped hole in the stained-glass window at the foot of the landing. Through it, the spindly black fingers of trees swayed in a night breeze, scratching amiably at the star-strewn sky.
"What is going on up there?" a raspy voice called, vibrating with rage. James scrambled to his feet, being careful not to step on any of the broken glass with his bare feet. Gingerly, he edged as close to the hole as he could and peered down. It was hard to tell how high the window was. There was no noise from the night except the hiss of the wind in the treetops.
Mrs. Norris the cat streaked up a nearby staircase, her orange eyes baleful as she flicked her gaze over the window, the broken glass, and then James. Mr. Filch followed, puffing and cursing as he climbed.
"Oh," he said, his voice dripping with sarcasm. "It's the Potter boy. Why, oh, why am I not surprised?"
"What were you thinking, Potter, chasing an unidentified individual, through the castle, at night, alone?" Headmistress McGonagall was standing behind her desk, leaning on it with both arms, ramrod straight. Her eyes were incredulous, her face scowling.
"I--" James began, but she raised one hand, stopping him.
"Don't answer. I've no patience for it this morning." She sighed and stood up straight, pushing up her glasses and pinching the bridge of her nose. "I've heard enough Potter explanations throughout the years to know the general shape of them, anyway."
Filch stood nearby, the jut of his jaw and the glint of his eye showing his pleasure at catching the latest Potter troublemaker so quickly. Mrs. Norris purred in his arms like a small, furry engine. James risked a look around the Headmistress' office. The room was still dim with very early morning shadows. The portraits of all the previous headmasters and headmistresses dozed in their frames. James could just see the portrait of his brother's namesake, Albus Dumbledore. Dumbledore was seated, his chin on his chest and his hat lowered over his eyes. His lips moved as he snored silently.
McGonagall lowered herself into her chair. "Mr. Potter, you, of all people, cannot tell me that you are not aware that there are rules against students wandering the school grounds at night."
"No," James said quickly. "Er, yes, I do know about the rules. But the ghost--"
McGonagall raised her hand again. "Yes, the ghost, I know." Everything except her actual words expressed doubt about that part of his story. "But Mr. Potter, you understand that even if a ghost appears in a student's bed chamber, that does not give said student a free pass to break whatever rules he deems temporarily inconvenient."
Mr. Filch stirred, seeming to decide that now was the time to press the point as he saw it. "He destroyed the Heracles window, Headmistress. Priceless bit of glasswork. We'll not find a replacement to match it, I'll wager." He sneered down at James as he finished.
"Windows are one thing, Mr. Filch," McGonagall said, not looking at him, "but intruders on school grounds are quite another. I presume you've already arranged an inspection of the campus, beginning with the area outside the Heracles window?"
"Yes, ma'am, and we've found nothing. The Venus Rose Gardens are immediately below that window. They're a bit of a mess, broken glass everywhere, but there's no sign of any intruder. We've only got this boy's word that there ever was such an intruder, Headmistress."
"Yes," McGonagall replied. "And unfortunately, in this case, that is a word I am inclined to trust. Someone obviously went through that window, unless you are suggesting that Mr. Potter himself came in through it."
Filch ground his teeth and glared at James as if he wanted very much to suggest such a possibility.