“Full of Dark Magic?” he repeated mildly. “Do you really think so, Severus? It looks to me as though it is merely a piece of parchment that insults anybody who reads it. Childish, but surely not dangerous? I imagine Harry got it from a joke shop—”

“Indeed?” said Snape. His jaw had gone rigid with anger. “You think a joke shop could supply him with such a thing? You don’t think it more likely that he got it directly from the manufacturers?”

Harry didn’t understand what Snape was talking about. Nor, apparently, did Lupin.

“You mean, by Mr. Wormtail or one of these people?” he said. “Harry, do you know any of these men?”

“No,” said Harry quickly.

“You see, Severus?” said Lupin, turning back to Snape. “It looks like a Zonko product to me—”

Right on cue, Ron came bursting into the office. He was completely out of breath, and stopped just short of Snape’s desk, clutching the stitch in his chest and trying to speak.

“I—gave—Harry—that—stuff,” he choked. “Bought—it . . . in Zonko’s . . . ages—ago . . . ”

“Well!” said Lupin, clapping his hands together and looking around cheerfully. “That seems to clear that up! Severus, I’ll take this back, shall I?” He folded the map and tucked it inside his robes. “Harry, Ron, come with me, I need a word about my vampire essay—excuse us, Severus—”

Harry didn’t dare look at Snape as they left his office. He, Ron, and Lupin walked all the way back into the entrance hall before speaking. Then Harry turned to Lupin.

“Professor, I—”

“I don’t want to hear explanations,” said Lupin shortly. He glanced around the empty entrance hall and lowered his voice. “I happen to know that this map was confiscated by Mr. Filch many years ago. Yes, I know it’s a map,” he said as Harry and Ron looked amazed. “I don’t want to know how it fell into your possession. I am, however, astounded that you didn’t hand it in. Particularly after what happened the last time a student left information about the castle lying around. And I can’t let you have it back, Harry.”

Harry had expected that, and was too keen for explanations to protest.

“Why did Snape think I’d got it from the manufacturers?”

“Because . . . ,” Lupin hesitated, “because these mapmakers would have wanted to lure you out of school. They’d think it extremely entertaining.”

“Do you know them?” said Harry, impressed.

“We’ve met,” he said shortly. He was looking at Harry more seriously than ever before.