Filch started to climb the stairs, his scrawny, dust-colored cat at his heels. Mrs. Norris’s lamp-like eyes, so very like her master’s, were fixed directly upon Harry. He had had occasion before now to wonder whether the Invisibility Cloak worked on cats . . . Sick with apprehension, he watched Filch drawing nearer and nearer in his old flannel dressing gown—he tried desperately to pull his trapped leg free, but it merely sank a few more inches—any second now, Filch was going to spot the map or walk right into him—

“Filch? What’s going on?”

Filch stopped a few steps below Harry and turned. At the foot of the stairs stood the only person who could make Harry’s situation worse: Snape. He was wearing a long gray nightshirt and he looked livid.

“It’s Peeves, Professor,” Filch whispered malevolently. “He threw this egg down the stairs.”

Snape climbed up the stairs quickly and stopped beside Filch. Harry gritted his teeth, convinced his loudly thumping heart would give him away at any second . . .

“Peeves?” said Snape softly, staring at the egg in Filch’s hands. “But Peeves couldn’t get into my office . . . ”

“This egg was in your office, Professor?”

“Of course not,” Snape snapped. “I heard banging and wailing—”

“Yes, Professor, that was the egg—”

“—I was coming to investigate—”

“—Peeves threw it, Professor—”

“—and when I passed my office, I saw that the torches were lit and a cupboard door was ajar! Somebody has been searching it!”

“But Peeves couldn’t—”

“I know he couldn’t, Filch!” Snape snapped again. “I seal my office with a spell none but a wizard could break!” Snape looked up the stairs, straight through Harry, and then down into the corridor below. “I want you to come and help me search for the intruder, Filch.”

“I—yes, Professor—but—”

Filch looked yearningly up the stairs, right through Harry, who could see that he was very reluctant to forgo the chance of cornering Peeves. Go, Harry pleaded with him silently, go with Snape . . . go . . . Mrs. Norris was peering around Filch’s legs . . . Harry had the distinct impression that she could smell him . . . Why had he filled that bath with so much perfumed foam?

“The thing is, Professor,” said Filch plaintively, “the headmaster will have to listen to me this time. Peeves has been stealing from a student, it might be my chance to get him thrown out of the castle once and for all—”

“Filch, I don’t give a damn about that wretched poltergeist; it’s my office that’s—”

Clunk. Clunk. Clunk.

Snape stopped talking very abruptly. He and Filch both looked down at the foot of the stairs. Harry saw Mad-Eye Moody limp into sight through the narrow gap between their heads. Moody was wearing his old traveling cloak over his nightshirt and leaning on his staff as usual.

“Pajama party, is it?” he growled up the stairs.