The Infernal Devices trilogy, a prequel to bestselling The Mortal Instruments trilogy, follows 16-year-old orphan Tessa Gray, whose quiet life is ... Show synopsis The Infernal Devices trilogy, a prequel to bestselling The Mortal Instruments trilogy, follows 16-year-old orphan Tessa Gray, whose quiet life is thrown into turmoil when her older brother Nathaniel suddenly vanishes, leaving her alone. Tessa's search for him takes her to England during the reign of Queen Victoria, into London's dangerous underworld, where warlocks throw masked balls for halfdemon Downworlders and vampires and supernatural folk stalk the gaslit streets. When the friendless and hunted Tessa discovers that she herself is a Downworlder, she must learn to trust her natural enemies, the demon-killing Shadowhunters, if she ever wants to learn to control her powers and find her brother. Drawn ever deeper into their world, she finds herself fascinated by - and torn between - two best friends; beautiful Will, a Shadowhunter hiding a deadly secret, and the devoted Jem, whose addiction to a demon drug is slowly destroying him. Tessa quickly realises that love may be the most dangerous magic of all and must draw on all her strength to save her brother and keep herself alive in this deadly new world.