Curse of Kalarel
The head librarian is Armani Darling.
The party met one of the guards on their last visit.
Candlekeep is the largest library in the entire continent of Hoff.
To get a library card, one must simply provide a rare, published book that the library does not have a copy of. It used to be easy to get in, but is more difficult now. Sheldon Lon is currently resting here in his magical sleep (he is a pre-existing member of the library).
With time you can research things here.