Clockwork Angel is the first book in Cassandra Clare’s historical fantasy trilogy The Infernal Devices, a prequel to the internationally bestselling series The Mortal Instruments. Clockwork Angel was first published in 2010, followed by Clockwork Prince in 2011 and Clockwork Princess in 2013. The trilogy follows Theresa (Tessa) Gray, an American girl in Victorian London, who discovers she is a member of the Shadow World, the hidden world of supernatural creatures, angels, and demons. Clockwork Angel debuted at #1 on the New York Times Children’s Series bestsellers list.

This guide references the 2015 paperback edition of Clockwork Angel, published by Margaret K. McElderry Books.

Content Warning: This guide describes and discusses the source text’s treatment of alcohol, substance, and gambling addictions.

Plot Summary

In April 1878, Theresa (Tessa) Gray lands in England to join her brother, Nathaniel (Nate), in London following the death of their Aunt Harriet. She expects to meet her brother at the docks, but ’she is instead greeted by two women, Mrs. Dark and Mrs. Black, and their strange coachman. The women convince Tessa that they were sent by her brother and then load her into a carriage marked with two serpents eating each other’s tails, an ouroboros symbol. Elsewhere in London, two teenage Shadowhunters—part-angel protectors of the supernatural realm—stumble on the murder of a young girl. William (Will) Herondale and James (Jem) Carstairs are too late to save the girl, but they find a mysterious dagger marked with the twin serpent symbol.

Six weeks later, Tessa is still imprisoned at the Dark Sisters’ home, threatened to obey all their commands or else her brother will be killed. The only other beings in the house are the coachman and the servant, Miranda, an automaton. During this time, the Dark Sisters have unlocked Tessa’s ability to shape-shift and are training her through vicious experiments to develop her power. The Dark Sisters give Tessa objects belonging to the dead, and Tessa uses her power to Change into those people, getting glimpses of their voices, personalities, or final moments. When Tessa successfully Changes into a young girl, Emma Bayliss, and recounts her death at the hand of the serpent dagger, the Dark Sisters declare that Tessa’s training is complete. The Sisters reveal that they have been training Tessa to marry a man called The Magister. The night Tessa tries to escape, she meets Will Herondale, who has found the Dark Sisters through Emma Bayliss’s murder investigation. Will helps Tessa escape and brings her to The Institute, the Shadowhunters’ headquarters in London.

At the Institute, Tessa meets the other Shadowhunters: Jem, Charlotte, Henry, and Jessamine. Charlotte, the head of the Institute, promises to help Tessa find her brother while they continue the investigation. Will and Jem, who both develop feelings for Tessa, help educate her about the Shadowhunter world and encourage her to embrace her powers. Meanwhile, Charlotte and Henry meet with Nate’s former employer, Axel Mortmain, and discover that Mortmain introduced Nate to the Shadow World through the Pandemonium Club, an establishment run by The Magister. Mortmain suggests that Alexei de Quincey, the head of a vampire clan and prominent businessman in the Club, may be The Magister. Another local vampire informant, Camille Belcourt, tells the Shadowhunters that de Quincey has been hosting human-torturing parties unbeknownst to the Clave, the Shadowhunter law enforcement. She suggests that Tessa shape-shift and attend one of the parties disguised as Camille so that the Clave can collect evidence against de Quincey. Tessa agrees.

Tessa attends de Quincey’s party as Camille with Will posing as her human subjugate. With the help of the warlock Magnus Bane, they search the house and discover blueprints for animating clockwork automatons with demonic energy. They witness de Quincey threatening a human whose face is covered by a bag, and Will signals for the Clave to raid the party. When the raid begins, the bag falls off the human’s head to reveal Tessa’s brother, Nate. Tessa and Will both almost die at de Quincey’s hands, but the Clave subdues the vampires and rescues Nate, returning him to the Institute with Tessa. They are unable to capture de Quincey but hope that Nate will be able to share information once he regains consciousness. That evening, Will and Tessa kiss, but Will abruptly sends her away without explanation.

When Nate awakens, he explains that de Quincey manipulated him using his debt to the Pandemonium Club, threatening to kill him if he did not send for Tessa. According to Nate, de Quincey and Mortmain knew their parents from the Pandemonium Club and had a suspicion about her powers. Nate tells the Shadowhunters that de Quincey and the Dark Sisters have mastered the demonic animation spell and plan to raise an army of automatons to destroy the Clave. Charlotte, Henry, and the Clave all rush to the address given to them by Nate. Not long after they leave, Mortmain shows up at the Institute to tell Will and Jem that there is a second location where the Dark Sisters are performing their ritual. Will and Jem leave Tessa, Jessamine, and Nate at the Institute, hopeful that they can interrupt the ritual in time. Once Will and Jem leave, Mortmain attacks the Institute with his automatons, revealing himself as The Magister and Nate as his servant.

Will and Jem arrive at the Dark Sisters’ home to find it empty except for Mrs. Dark, who is trying to resurrect her sister. They realize they have been deceived and race back to the Institute. Meanwhile, Mortmain threatens to kill Jessamine and the Institute servants if Tessa does not give herself up. He claims he created her by manipulating her mother into a union with a demon. Tessa refuses to obey Mortmain and pretends to stab herself to catch him off guard. Her plan works, and Will arrives in time to apprehend Mortmain. Nate escapes, taking the Institute’s storage of demonic energies with him.

Tessa and the Shadowhunters must give an account of the battle to the Clave, who will continue investigating. Charlotte invites Tessa to remain at the Institute and Tessa agrees. When Tessa finds Will to celebrate with him, he rejects her. Hurt, Tessa finds Jem, who alludes to his own feelings for her. At the close of the story, Tessa’s clockwork angel pendant, a gift from her mother, finds its way back to her, having disappeared during the battle.