Every book left unfinished by its author is filed away in the Unwritten Wing, a neutral space in Hell presided over by Claire, its head librarian. Along with repairing and organizing books, her job consists of keeping an eye on restless stories whose characters risk materialising and escaping the library.

When a Hero escapes from his book and goes in search of his author, Claire must track and capture him with the help of former muse and current assistant Brevity and nervous demon courier Leto. But what should have been a simple retrieval goes horrifyingly wrong, in a chase that threatens to reshape the boundaries between Heaven, Hell... and Earth.