Going straight through the Kitchen (as opposed to turning left, where there was a door being 'tested' by someone on the other side) the River Gang came to a smallish guard-room. There were three Beast Boy mercenaries there, but they had already been informed by the Cook's assistant that the group was on its way, and they made only begrudging nods at the new arrivals. Two long hallways extended to the right and left of the guard-room. To the right, a long tunnel led to the Watchtower, while to the left a narrow corridor led to a single small door.
"That would be the Library." Bardaby informed them. "In all my time here, no one has ever used that door for any reason. It is locked, probably barred. Unless he's gone to see what all the fuss is, it's almost certainly got Murlien the Necromancer behind it, working on Gods-know-what."