When Harry asked why he was in Knockturn Alley, Hagrid scratched his large, shaggy head. "Me? I came looking for something to get rid of Flesh-Eating Slugs. They've nearly ruined all the school's cabbages..."
As he spoke, Hagrid pulled Harry into a little alley. "Professor Sprout told me there's a potion that'll work well. But they don't sell it anywhere else. Oh, Harry, has the Ministry of Magic found out who was intercepting your letters?"
"No." Harry pursed his lips. "But I already know. It was a House-elf called Dobby. Completely mad." Harry briefly repeated what he had already told Ron's family.
"A House-elf? Now that's unusual." Hagrid's thick eyebrows drew together slightly, and then he seemed to think of something.
"Harry, you need to be careful. There used to be wizards who trained House-elves as killers. It was banned later, but nobody knows whether anyone's still doing it. After all, some wizarding families don't care much about Ministry of Magic laws."
"Yes, Mrs. Weasley said that too. But she and Percy also said there probably aren't any House-elf assassins these days. I'll still be careful, though." Harry nodded to show he understood.
The two of them passed through the narrow alley, and the gloomy street suddenly gave way to a different sight.
They had reached Diagon Alley, and Harry could already see the top of Gringotts' distinctive white marble building. A little closer, he spotted Ron and Hermione standing at the entrance, looking anxiously around. They were clearly searching for him.
"Harry!" Hermione spotted him first and waved to him. Harry and Hagrid immediately strode toward them.
"Hi, Hagrid, long time no see." Once they were close, Ron and Hermione greeted Hagrid.
"Hi, Ron, have you grown again? And Hermione, hello to you too." Hagrid greeted them both happily.