"Back door, technically. For all intents and purposes, it’s an entrance" Draco replied darkly. "The actual entrance is considerably further in, behind an underwater waterfall. This one, it... well –" He caught Hermione’s wide brown eyes. "Nicolai and I haven’t made much headway in studying this particular entrance" he said evasively, looking up at the group, clearly hoping someone would say something to pull him out of what was becoming an uncomfortable conversation. 