The risk of being exposed is too great, so you head left towards the library.

Given the state of the fortress you've seen so far, the library is in surprisingly good repair. The saccharine stench of mold and rot is less prominent here, replaced by the musty smell of old paper and leather. The room is quite tall, nearly three stories high from floor to ceiling, and well lit with what appear to be magic lanterns. The lights flicker enough to convincingly resemble flames, but give off no heat - it is actually quite cold.

The library is a circular room, with bookshelves arranged around the perimeter and forming aisles that point towards the room's center - each bookshelf also has an opening halfway along its length to grant access between the aisles. At the center of the room is a ring-shaped desk, stacked with hefty volumes, quills, and vials of ink.

Perched in the center of the desk is a plump, feathered woman - a harpy you suspect - engrossed by one of the large books on her desk. She's mostly facing away from you, giving you an excellent view of the two massive wings growing from her back; as she turns the book's pages, you notice that she has two smaller wings where her arms should be.

On the other side of the library, you can see a pair of large double doors, already ajar and leading deeper into the fortress. With how focused she is on her book, you are confident you could simply sneak around the outside edge of the library and slip through the door. In fact, you are just about to do so when you sense powerful astral energy emanating from the center of the room. The energy is being emitted periodically from an ornate glass case on the desk, which contains a large book with a gilded spine. That book seems like it's very important, but you obviously can't just take it - you'd need to take care of the harpy, and that's risky.

You contemplate your options as the harpy reads absentmindedly, the only sound in the room being the occasional turn of a page...