In 1912, magic has nearly vanished, but Biddy, an orphan raised on the hidden island of Hy-Brasil, has known little else. Living with her guardian, the magician Rowan, she yearns for freedom beyond the island. When Rowan mysteriously disappears, Biddy must journey through his nightmares and uncover his dangerous enemies. Her search leads her from the slums of Whitechapel to a secret castle beneath London and the ruins of an ancient civilization. As she fights to protect Rowan and restore magic to the world, Biddy discovers unsettling truths about her guardian, her own origins, and the true cost of reviving magic.