or --" He broke off with a small gasp, looking over Harry's shoulder.

 It was Snape. Neville took a quick step behind Harry. 

"And what are you two doing here?" said Snape, coming to a halt and looking from one to the other. "An odd place to meet --" 

To Harry's immense disquiet, Snape's black eyes flicked to the doorways on either side of them, and then to the one-eyed witch. 

"We're not -- meeting here," said Harry. "We just -- met here." 

"Indeed?" said Snape. "You have a habit of turning up in unexpected places, Potter, and you are very rarely there for no good reason.... I suggest the pair of you return to Gryffindor Tower, where you belong." 

Harry and Neville set off without another word. As they turned the corner, Harry looked back. Snape was running one of his hands over the one-eyed witch's head, examining it closely. 

"Amelia was raised by vampires, and she's a lot better at this test-taking stuff than I am especially when it comes to magical creatures. She could help you when she gets back."

"Thanks, I'll ask her. But do you think you could help me with this part here-"

Harry managed to shake Neville off at the Fat Lady by telling him the password, then pretending he'd left his vampire essay in the library and doubling back. Once out of sight of the security trolls, he pulled out the map again and held it close to his nose. 

The third floor corridor seemed to be deserted. Harry scanned the map carefully and saw, with a leap of relief, that the tiny dot labeled Severus Snape was now back in its office. 

He sprinted back to the one-eyed witch, opened her hump, heaved himself inside, and slid down to meet his bag at the bottom of the stone chute. He wiped the Marauder's Map blank again, then set off at a run. 

Harry, completely hidden beneath the Invisibility Cloak, emerged into the sunlight outside Honeydukes and prodded Ron in the back.

" It's me," he muttered.