After being swept up in the world of The Central Library, Emerson Blackwell has finally stepped into Foundation's Catalogue.

The worlds she encounters inside the banned books are darker, but no less real, than the realms in The Central Library's Catalogue. Emerson finds herself thrown headfirst into a Catalogue brimming with monsters from her worst nightmares, tests that make her question reality, and enemies disguised as friends.

Emerson made a split-second decision in her desperation for the truth, but curiosity soon turns to unease when she is forced to confront what awaits her inside Foundation. Where she expected to find answers, there are only more questions. Iris Blackwell may be alive and well, but the mother she remembers is a distant memory. Old feelings begin to resurface for Silas Rathbone as her time inside the banned books distorts the memories of Adrien Moon. And with every new world she discovers, the more she begins to wonder whether the books are transforming her into someone she no longer recognizes.

Only one thing becomes clear the further Emerson dives inside Foundation's Catalogue: Villains are not born. They are made.