Following the map's directions, Roy made his way to the underground river where first-years entered the castle, then retraced the hidden passage they had once taken to the surface. He returned to the Underground Dock hidden beneath the ground and found the entrance to the Hogwarts dungeons marked on the map.
Hogwarts Castle actually had a very deep underground structure. Every student was familiar with the first basement level, where the Potions classrooms, Slytherin Common Room, and Hufflepuff Common Room were located.
But as for the deeper levels underground, even many seventh-years had only heard that there were dungeon-like areas beneath the castle. No one had ever truly seen them.
In fact, hundreds of years ago, the school had sealed every passage leading to the dungeons. Even a century ago, that fifth-year god of slaughter had needed to detour through the Underground Dock, the only entrance, to get inside.
The so-called underground classrooms in the castle today were the portion of the old dungeons that had been preserved rather than sealed off. Most of the space had been converted into Potions classrooms.
Arriving before a giant wooden door covered in rust and dust, Roy gave it a quick look. Seeing the huge corroded lock hanging from the handle, he tried Alohomora. As expected, it would not open.
But Roy clearly had a backup plan. Picking locks was effortless for him. He pulled out the lockpicking tools he had prepared in advance and, after only a few movements, removed the massive brass lock.
The path to the dungeons was finally unobstructed. Roy forcefully pushed open the decrepit doors before him, revealing a deep, shadowy passage.
The entrance was pitch-black, without the slightest trace of light. It was impossible to see what lay within. The open doors seemed like an entrance leading