The Citadel of Chaos

He points to a section just above the floor, which you peruse.
Eventually you choose one volume and settle down to read through it.
Balthus Dire is apparently third in a line of Sorcerer-Warlords
ruling over the Black Tower and the Kingdom of Craggen Rock.
He rose to power after the death of his father, Craggen Dire, some years ago.
The Dires have been masters of Black Sorcery for generations,
but their strength and power last during the night-time only; sunlight is like a poison to them.
Shortly after his father's death, Balthus Dire married the Lady Lucretia,
herself a Black Sorceress, and since that time they have ruled together over the Kingdom of Craggen Rock.
As you finish the book, you notice that the librarian is holding his hand to his ear,
apparently listening to something.
He glances up at you, quizzically.

You may either look for another useful book which may aid you on your quest,

or attempt to leave the library through the door behind him.