Magic is a dangerous game, especially in the fog-drenched streets of Victorian London. When sixteen-year-old Tessa Gray arrives in England, she expects to find her brother. Instead, she is plunged into London's terrifying Downworld, a hidden society where vampires, warlocks, and supernatural creatures stalk the gaslit alleys. Hunted for a rare and mysterious power she never knew she possessed, Tessa has no choice but to seek refuge with the Shadowhunters, a fierce band of warriors sworn to rid the world of demons. Within the walls of the London Institute, Tessa finds herself drawn to two very different best friends: the handsome, tortured Will and the gentle, devoted Jem. As dark forces gather to destroy the Shadowhunters, Tessa must learn to harness her newfound abilities while navigating a treacherous web of love, loyalty, and betrayal.