The Gatlin Library is a location in the small town Gatlin.
Lena inside the Caster Library.
It is were Marian works and was originally run by Ethan's late mother, Lila Evers Wate.
Unknown to most of the town's residents, beneath the ordinary library was the Caster Library. Another hidden part of it which contained books about the Caster world such as cast books and scrolls, the infamous Caster Chronicles (a book which contains lists of famous Casters), The Book of Moons, Light and Dark talismans and etc. Olivia Durand, was originally being trained to be the next fellow Keeper of the Caster library (as Marian was the current one being in charge of it) until she was expelled from her soon-to-have-been position for participating in a Cast with Ethan. Since Keepers are not to become involved in such a thing; only learning about it.