|Cover artist||Cliff Nielsen|
|Release Date||August 31, 2010|
|Publisher||Margaret K. McElderry Books|
| Preceded by|
| Followed by|
| Released after|
City of Glass
| Released before|
City of Fallen Angels
Magic is dangerous — but love is more dangerous still.
When sixteen-year-old Tessa Gray crosses the ocean to find her brother, her destination is England, the time is the reign of Queen Victoria, and something terrifying is waiting for her in London's Downworld, where vampires, warlocks and other supernatural folk stalk the gaslit streets. Only the Shadowhunters, Nephilim warriors dedicated to ridding the world of demons, keep order amidst the chaos.
Kidnapped by the mysterious Dark Sisters, members of a secret organization called the Pandemonium Club, Tessa soon learns that she herself is a Downworlder with a rare ability: the power to transform, at will, into another person. What's more, the Magister, the shadowy figure who runs the Club, will stop at nothing to claim Tessa's power for his own.
Friendless and hunted, Tessa takes refuge with the Shadowhunters of the London Institute, who swear to find her brother if she will use her power to help them. She soon finds herself fascinated by and torn between two best friends: Jem, whose fragile beauty hides a deadly secret, and blue-eyed Will, whose caustic wit and volatile moods keep everyone in his life at arm's length...everyone, that is, but Tessa. As their search draws them deep into the heart of an arcane plot that threatens to destroy the Shadowhunters, Tessa realizes that she may need to choose between saving her brother and helping her new friends save the world... and that love may be the most dangerous magic of all.
In London 1878, parabatai Will Herondale and Jem Carstairs find the dead body of fourteen-year-old Emma Bayliss in an alley. An investigation of the dagger found with her body and the symbol of a double ouroboros leads them to the Pandemonium Club.
Meanwhile, Tessa Gray, still grieving from the death of her Aunt Harriet Moore, has just arrived at Southampton to meet with her brother, Nate. Instead of Nate, however, Tessa is greeted by the Dark Sisters, Mrs. Dark and Mrs. Black, who then insist that they are there to pick her up for Nate. Accompanying them is a mysterious coachman with bulging eyes, who leaves an odd impression on Tessa. Hoping to see her brother, Tessa agrees to go with them.
Six weeks later, Tessa is still held prisoner by the Dark Sisters, training her to "Change", or shapeshift—an ability which Tessa still cannot explain why she has. The sisters give her personal items of the persons they want her to Change into, and, eventually, Tessa learns to control her power.
One evening, Tessa is asked to become Emma Bayliss, a girl whose existence is apparently threatening to the sisters. Tessa relives Emma's last few moments alive. The sisters are impressed and tell Tessa that they have been preparing her for an arranged marriage to a mysterious individual known as "the Magister." They expect the marriage to take place that day or the next. The sisters leave and Tessa tries to run away. She hits the servant Miranda, who tries to stop her, but is caught by the Sisters' coachman.
Tessa is then tied to her bed but is able to break away from her binds by Changing into the small Emma. Hearing someone outside, Tessa hides behind the room's door and hits the intruder: Will Herondale, whose investigation of the Pandemonium Club led to the Dark Sisters' home. After a confusing first introduction, including Will cursing at her, quoting poetry and comparing himself to the fictional character, Sir Galahad, Will declares that he will help Tessa escape. The Dark Sisters catch up and a battle breaks out. Two other Shadowhunters who came with him arrive and join the fight, in which Mrs. Black is killed and Tessa is knocked unconscious.
When Tessa comes to, she is at the London Institute and being studied by Brother Enoch, a Silent Brother, who informs her that she is either a Downworlder, seemingly a warlock, or Eidolon, but not quite because of her lack of a mark. Tessa is also introduced to the head of the Institute, Charlotte Branwell, whom Tessa almost immediately takes a liking to, her eccentric husband Henry, and the self-absorbed ward of the Institute, Jessamine Lovelace. She is also reunited with her savior, Will. Over dinner, her hosts try to find out what she is, while explaining what they are—Shadowhunters, or Nephilim, a race who hunt demons—and the mysteries of the veiled world they live in. They tell her that she has their assistance in finding her brother, which they believe has a connection to their ongoing investigation into Emma Bayliss' death. Tessa then demonstrates her ability by changing into Jessamine.
Losing her way in the Institute, Will gives her a tour, introducing her to their servants Agatha and Thomas along the way. At the library, Tessa learns more about Will and they seem to bond. Intending to walk her to her room, Will's mood suddenly shifts when, after an encounter with Sophie, he snaps at Tessa's remarks and leaves her to find her own way back to her room.
Reading the Shadowhunter's Codex in her room until she falls asleep, she is awakened by the beautiful sounds of a violin. She peeks into the source of the music and meets Will's parabatai, Jem Carstairs. The two converse briefly until an apparently inebriated Will arrives. When Jem suddenly begins having a coughing fit, a worried Will sends Tessa away.
The next morning, Sophie helps Tessa get into Jessamine's discarded dress. The Shadowhunters then discuss their next course of action. Charlotte and Henry decide to visit Axel Mortmain, Nate's employer and a possible lead, and they assign Will and Jem to further inspect the Dark Sisters' house. An uninterested Jessamine volunteers to take Tessa shopping to skirt her responsibilities.
Jem and Will then proceed to the Dark House, where they find what they think is a dead woman, Miranda. After it speaks to them, its skin begins to unravel and they see that it is in fact not human, but similar to Henry's machines and gadgets at home, a sight both strange and new to the pair, so they take her back to the Institute.
Charlotte and Henry's investigation proves fruitful when Mortmain, who knows strangely a great deal about the Downworld, tells them that Nate has taken an interest in the Pandemonium Club, much like he has. He tells them that the head of the organization calls himself "the Magister." When Henry bluffs and threatens to unleash the wrath of the Clave by summoning them with his invention, the "Summoner", Mortmain fearfully names the Magister as de Quincey, whose name Charlotte recognizes as the head of a powerful London vampire clan, who also happens to be an influential Downworlder and apparent ally of the Clave.
Meanwhile, after buying clothes, Jessamine takes Tessa to the park. Over the course of their time together, Tessa learns more about why Jessamine seems embittered about being a Shadowhunter. At the park, they are attacked by a goblin, which Jessamine grudgingly kills.
Back at the Institute, Henry has opened Miranda up to study it. He finds out, and later tells Tessa that Miranda is in fact an automaton, merely wrapped in actual human flesh, most likely those of the bodies they found at the Dark House.
Later, another vampire, Lady Camille Belcourt, comes to the Institute and informs them that de Quincey has been throwing parties where he tortures and kills humans by drinking their blood for entertainment, thus breaking the Accords. However, the Shadowhunters realize that they need to catch him in the act of breaking the law before making a move against him, since de Quincey has been considered an ally of the Clave for so long. Camille admits that her motives for coming forward was revenge against de Quincey who killed her lover, and also to meet Tessa, who has become very talked-about in Downworld, and reveals that Tessa's brother may be with de Quincey.
Will and Tessa decide that the only way that they can attend the party without causing a stir is for Tessa to attend the party disguised as Camille, with Will posing as her human subjugate. Camille also says that her lover, the warlock Magnus Bane will attend the party with them for assistance.
The Enclave gathers at the library to discuss the plan, and they agree to allow Tessa and Will to infiltrate de Quincey's home, and wait outside for a signal.
At the party, Magnus informs Will and Tessa about some plans for a demonic clockwork army found in the library, but they are forced to join the other vampires in another room before they can discuss the matter further. The room is set up to host one of de Quincey's 'performances' but as the human is revealed to be Nate, Tessa blows her cover in an attempt to save her brother. Will summons the other Shadowhunters, who fight and kill the vampires. Will confronts de Quincey as he attacks Camille/Tessa, and bites him, mocking him and asking the vampire how it feels to be on the receiving end of one. Infuriated, De Quincey manages to escape, and Will accidentally consumes some of the vampire's blood because of the bite. They also save Nate and bring him back to the Institute.
Back at the Institute, he and Tessa share a passionate moment where they kiss when she brings him holy water to drink to cleanse his body of the vampire blood, but he abruptly ends their kiss and sends her away. Tessa leaves, confused and dazed.
Unaware of these events, Jem cheers up Tessa and takes her to his favorite place in London, where they are attacked by members of the Magister's clockwork army. They make it to the Institute, but Jem collapses before he can open the door. Tessa manages to alert the Shadowhunters inside, but not before one of the clockwork figures smears his hand with the blood from Jem's injuries. The figure waves in a grotesque manner before retreating.
Later, Tessa is summoned to Jem's room, and he explains why he collapsed earlier; when he was living in China, a greater demon broke into their home and tortured Jem in front of his parents as an act of revenge against his mother, who had raided the demon's nest and killed it's babies. It tortured him by constantly feeding him a demon drug that caused him to hallucinate for days. He was found by some other Shadowhunters, but his parents had been killed. Jem admits that his body is now addicted to the drug and he has to take some of it every day, causing his skin, hair and eyes to pale to a silver color, and without it his body cannot function. He did not take any when he was out with Tessa, which was why he collapsed. He also tells Tessa that the drug is killing him, but when Tessa asks him why he does not simply give up his dangerous profession, he declares that "there are more things to life than not dying".
The following day, most of the Shadowhunters leave to kill de Quincy in his hideaway in Chelsea. Mortmain, the mundane who informed the Shadowhunters of de Quincey, comes back to the Institute to tell Will and Jem about the Dark sister who is trying to help the Magister with his army and her location. They rush off to kill her, leaving Nate, Jessamine and Tessa alone with Sophie, Agatha and Thomas.
Mortmain comes back with the clockwork army, using Jem's blood from the clockwork figure's hand to gain access, and reveals himself as the real Magister. Nate reveals himself as Mortmain's accomplice. While Thomas tries to fight the clockwork automatons off, Tessa, Sophie and later Jessamine escape to the Sanctuary, but Mortmain tricks Jessamine into opening the door by disguising his voice as that of Will's. Tessa agrees to marry Mortmain to spare Sophie and Jessamine's lives. Mortmain, believing he has won, agrees, but once the army has left the room, Tessa stabs herself in the heart and falls into the fountain.
Will rides back once he realizes he and Jem have been tricked, leaving Jem to ride the carriage with only one horse, slowing him down. When Will arrives at the Institute, he's just in time to witness Thomas' death and after thanking him for everything that he has done, goes on to look for Tessa and the others. While Jem arrives, he runs straight into Nathaniel and his four clockwork automatons, two of them holding Jessamine and Sophie, and one holding the Pyxis, a box that holds demon energies needed to revive the automatons. Nate orders the army to kill him - Jem fights them off, but Nathaniel and the Pyxis flee, just before Charlotte and Henry come to help Jem finish of the automatons. Charlotte reveals that de Quincey had laughed at the Enclave for mistaking him for The Magister.
At the same time, Will finds Tessa and Mortmain in the Sanctuary; Tessa, bleeding to death in the fountain, Mortmain, kneeling beside her. Will lunges at Mortmain but he disappears. Will breaks down and mourns her death. Tessa then awakens in his arms and reveals that she tricked the Magister into believing that she was dead by changing just before she pretended to stab herself; she changed into a gunshot victim she had previously changed into whilst living with The Dark Sisters; the dead woman's blood had poured down Tessa's chest, looking like she had wounded herself.
After Thomas and the others are buried, Tessa thanks Charlotte for her hospitality, but assumes that she is going to be asked to leave. Instead, Charlotte asks Tessa to stay, an offer that she accepts.
Tessa goes to Will wanting to have a serious relationship after he confirmed his feelings for her in the Sanctuary, but he cruelly suggests that while he'd be open to sleeping with her, they'd never have any real relationship, since there is no future for a Shadowhunter who dallies with warlocks. He then points out the fact that as a warlock, she is not able to bear children. Tessa is horrified because this is the first time that she has heard this, and runs away from Will.
Jem finds and comforts her, saying that although she feels that she is unlovable because she is not human, "The right man won't care" subtly declaring his feelings for her. (Jem is completely unaware of the complicated relationship between Tessa and Will.) Tessa gratefully accepts Jem's comfort, but does not completely realize the sincerity behind his words. The clockwork angel (the necklace around Tessa's neck, which was lost during the chaos of the battle in the Institute), flies back to Tessa's arms.
The story concludes with a deeply distressed Will turning up at Magnus Bane's temporary residence (Camille Belcourt's House) asking for help, the issue is unknown as the epilogue ends.
- Tessa Gray - the main protagonist of the series, Tessa is a warlock who grew up in the mundane world.
- Camille Belcourt - a beautiful old vampire and informant of the London Institute who has a score to settle with an old friend, the leader of her clan.
- Magnus Bane - the lover of Camille, Magnus would be a helper to Tessa and the Shadowhunters of the London Institute, particularly Will Herondale.
- Alexei de Quincey - the powerful leader of the vampire clan in London who has been throwing parties to deliberately and publicly renounce the Nephilim Law and the terms of the Accords.
- Dark Sisters - Mrs. Black & Mrs. Dark; a pair of demonic sisters with connections to the Pandemonium Club.
- Will Herondale - Will is the seemingly carefree ward of the Institute who is intent on pushing others away.
- Jem Carstairs - Will's parabatai, Jem is a ward of the Institute whose life depends on a drug that also slowly kills him.
- Charlotte & Henry Branwell - the heads of the London Institute.
- Jessamine Lovelace - a ward living in the London Institute who is unhappy with the life of the Shadowhunters and wishes only to become a mundane.
- Brother Enoch - the Silent Brother most called upon by the London Institute.
- Nate Gray - Tessa's trouble-prone brother who was apparently abducted by the Magister.
- Axel Mortmain - the wealthy and very influential mundane that employed Nate under suspicious circumstances.
- Sophie Collins - the maidservant of the ladies in the London Institute who becomes a good friend to Tessa.
- Thomas Tanner - a servant in the London Institute who has trained with the Shadowhunters and has feelings for Sophie.
- Agatha - the cook of the London Institute.
The Infernal Devices has been optioned for film by Constantin Film, the same studio that produced The Mortal Instruments: City of Bones. On April 12, 2013, it was announced that Stephanie Sanditz was hired to pen the script for the film adaptation of the book. An update from Cassandra Clare states that the series might be adapted into a TV series.
- The original (now hardbound) cover features Will Herondale, with the eponymous clockwork angel necklace in front of him, against a backdrop of London. The repackaged (paperback) cover also features Will, this time on his knees with torn and stained clothes, drawing a sword from its sheath, with an illustration of the clockwork angel standing behind him.
- The cover model for Will on the original US cover is Danny Schwarz.
- The poetry quotations at the beginning of each chapter are from poetry that Tessa would be familiar with, except the poems by Wilde and Kipling—which were from later than 1878—and " " by Elka Cloke, which was written specifically for the book.