From the New York Times bestselling author of The Night Circus, a timeless love story set in a secret underground world—a place of pirates, painters, lovers, liars, and ships that sail upon a starless sea. Zachary Ezra Rawlins is a graduate student in Vermont when he discovers a mysterious book hidden in the stacks. As he turns the pages, entranced by tales of lovelorn prisoners, key collectors, and nameless acolytes, he reads something strange: a story from his own childhood. Bewildered by this inexplicable book and desperate to make sense of how his own life came to be recorded, Zachary uncovers a series of clues—a bee, a key, and a sword—that lead him to a masquerade party in New York, to a secret club, and through a doorway to an ancient library hidden far below the surface of the earth. What Zachary finds in this curious place is more than just a buried home for books and their guardians—it is a place of lost cities and seas, lovers who pass notes under doors and across time, and of stories whispered by the dead. Zachary learns of those who have sacrificed much to protect this realm, relinquishing their sight and their tongues to preserve this archive, and also of those who are intent on its destruction. Together with Mirabel, a fierce, pink-haired protector of the place, and Dorian, a handsome, barefoot man with shifting alliances, Zachary travels the twisting tunnels, darkened stairwells, crowded ballrooms, and sweetly soaked shores of this magical world, discovering his purpose—in both the mysterious book and in his own life.

Around the world, black hand prints are appearing on doorways, scorched there by winged strangers who have crept through a slit in the sky. In a dark and dusty shop, a devil’s supply of human teeth grows dangerously low. And in the tangled lanes of Prague, a young art student is about to be caught up in a brutal otherworldly war. Meet Karou. She fills her sketchbooks with monsters that may or may not be real, she’s prone to disappearing on mysterious "errands", she speaks many languages - not all of them human - and her bright blue hair actually grows out of her head that color. Who is she? That is the question that haunts her, and she’s about to find out. When beautiful, haunted Akiva fixes fiery eyes on her in an alley in Marrakesh, the result is blood and starlight, secrets unveiled, and a star-crossed love whose roots drink deep of a violent past. But will Karou live to regret learning the truth about herself?

The great city of Ebora once glittered with gold. Now its streets are stalked by wolves. Tormalin the Oathless has no taste for sitting around waiting to die while the realm of his storied ancestors falls to pieces - talk about a guilt trip. Better to be amongst the living, where there are taverns full of women and wine. When eccentric explorer, Lady Vincenza 'Vintage' de Grazon, offers him employment, he sees an easy way out. Even when they are joined by a fugitive witch with a tendency to set things on fire, the prospect of facing down monsters and retrieving ancient artefacts is preferable to the abomination he left behind. But not everyone is willing to let the Eboran empire collapse, and the adventurers are quickly drawn into a tangled conspiracy of magic and war. For the Jure'lia are coming, and the Ninth Rain must fall...