Eve Baird is after a group of criminals when she finds herself facing a bomb. Flynn Carson arrives out of nowhere and cracks an ancient code, which stops the bomb and allows him to retrieve the Opal of Samarra.

A mysterious man calls later looking for Flynn. He knows about the Opal and the library. Just as he is about to find Flynn, he is murdered.

Eve is alone in her apartment when she gets a mysterious letter inviting her to interview for a position at the Metropolitan Public Library. She arrives to the interview and learns that the Metropolitan is only the entrance to the "real" library which houses all of the world's magic.

She meets Flynn again and learns that they want her to be his guardian.

The two realize that the man who was murdered interviewed for the same position as librarian when Flynn interviewed. And now, other potential librarians are in danger.

They find other potentials, including Cassandra, who has a photographic memory and some useful hallucinations; Ezekiel, who is trying to steal a jeweled dagger when Flynn meets him; and Jacob, who is an expert in both art history and bar fighting.

The group works together to find out who is after them, and thanks to Jacob's knowledge of art, the realize that the Serpent Brotherhood are after the Crown of King Arthur. They set off to find the crown and recover it after a few obstacles.

Unfortunately, the Serpent Brotherhood is let into the library by Cassandra. Flynn is injured by Excalibur, and Judson and Charlene make a rash move to save the library.