One of them sparked a cigarette as they passed by where she was hiding, and Hermione instinctively backed away from them. They didn't see her. She let out a massive exhale as the sound of the metal door thudded shut. In her haste to back away from their light, Hermione nearly lost her footing and fell further into the darkness. As she righted herself, she realized that she was standing on a stone staircase.