"Shadowmarch" is a fantasy novel written by Tad Williams. It is the first book in the Shadowmarch series, which explores a richly detailed world filled with magic, political intrigue, and mythical creatures. The story follows the lives of two royal siblings, Barrick and Briony, as they navigate the challenges of their kingdom and the looming threat of an ancient enemy. Set in the land of Eld, the narrative intertwines various characters and their struggles against dark forces. The novel delves into themes of power, loyalty, and the complexities of human nature, making it a compelling read for fans of the fantasy genre.