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 an alley near Whitechapel, parabatai Will Herondale and Jem Carstairs are fending off demons, when the latter discovers a dead body of fourteen-year-old mundane Emma Bayliss. 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 from New York City to Southampton to stay 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 at Nate's request. Accompanying them is a mysterious coachman with bulging eyes, who leaves an odd impression on Tessa. However, hoping to see her brother, Tessa agrees to go with them. She notices, however, that the carriage of the Dark Sisters also had the double ouroboros.
Six weeks later, Tessa is 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 objects associated with the people they want her to Change into, and eventually, Tessa learns to control her power.
One evening, she is asked to turn into Emma Bayliss, a girl whose existence is supposedly threatening the sisters. Tessa relives Emma's last few moments alive. The sisters are satisfied and relieved. They inform 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 very same day or perhaps the next one. They then depart and Tessa attempts to flee. She wounds the servant Miranda, discovering, in the process that the maid is not a human. Tessa nearly escapes, when she is caught by the Sisters' coachman.
Tessa is restrained and tied to her bed but breaks her bindings by Changing into the Emma again. Sensing someone outside, Tessa hides behind the door and injures the intruder: Will Herondale, whose investigation of the Pandemonium Club led him to the Dark House. 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 regains consciousness, she is at the London Institute and being studied by Brother Enoch, a Silent Brother, who informs her that she is not quite human; perhaps a Downworlder, seemingly a warlock, or an Eidolon demon, but she has no warlock mark whatsoever. Tessa is also introduced to the head of the Institute, Charlotte Fairchild, 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 who she is, while explaining that they are Shadowhunters, or Nephilim, a race who hunts demons and further explain, very briefly, mysteries of the veiled world they live in. Once Tessa reveals the events of the preceding two months, and the Sisters' business details, Charlotte assures her that she has their assistance in finding her brother, whom they believe has a connection to their ongoing investigation into Emma Bayliss as well as several other mundane deaths. When insulted by Jessamine, Tessa displays her ability to the occupants of the Institute for the first time.
She proceeds to her room to rest, but loses her way, and 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, and he snaps at Tessa's remarks and leaves her to find her way back to her room.
Reading the Shadowhunter's Codex in her room—which Will lent to her—until she falls asleep, she is awakened by the beautiful sounds of a violin.Trying to discover the source of the music, she encounters Will's parabatai, Jem Carstairs, who was absent during dinner. The two converse briefly until an apparently inebriated Will arrives. Jem suddenly begins having a coughing fit, and a worried Will sends Tessa away. Tessa notices, however, that even though Will claimed he was drunk, there was no smell of alcohol around him.
The next morning, it is decided that Tessa shall remain in the Institute for some more time. The Shadowhunters then discuss their next course of action. Charlotte and Henry decide to visit Axel Mortmain, Nate's former employer and a possible lead. He is also believed to have had connections with the Downworld and subsequently, the Pandemonium Club. Will and Jem are assigned the task to further inspect the Dark Sisters' house. Disinterested, Jessamine volunteers to take Tessa shopping as an excuse to remain excluded from the investigation process.
Jem and Will proceed to the Dark House, where they find who they think is a dead woman, Miranda. After she speaks to them, her skin begins to unravel and they see that Miranda is not human, but similar to Henry's machines and gadgets at home, a sight both strange and new to the pair; hence they take her back to the Institute.
Charlotte and Henry's investigation proves fruitful when Mortmain, who—strangely—knows a great deal about the Downworld, tells them that Nate had taken an interest in the Pandemonium Club, much like he himself had. He tells them that the head of the organization calls himself "the Magister", however he seems reluctant to disclose anything much. When Charlotte bluffs and threatens to unleash the wrath of the Clave by summoning them with Henry's invention, the "Summoner", Mortmain fearfully names the Magister as a vampire named de Quincey, who Charlotte recognizes as the head of a powerful London vampire clan, and 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 born a Shadowhunter. Jessamine believes that a lady's job was not to fight but to get married and carry out womanly duties. She attempts to convince Tessa into running away and hiding into the mundane world with her, but Tessa is scandalized and gently turns her down. At the park, they are attacked by a goblin, which Jessamine grudgingly kills with her parasol .
Back at the Institute, Henry opens up Miranda's body to study it. He finds out and later tells the others that Miranda is an automaton, merely wrapped in actual human flesh, most likely obtained from the body of the dead mundanes they had found at the Dark House.
Some time later, another vampire, Lady Camille Belcourt, calls on the Institute and informs the Shadowhunters and Tessa that de Quincey has been secretly throwing parties where he tortured and killed humans by drinking their blood for entertainment, which was a violation of the Accords. The Shadowhunters plan to expose him, but they instantly 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 were revenge against de Quincey who killed her former lover and also to meet Tessa, who has become a famous personality in the Downworld. SHe also hints that Tessa's brother might be with de Quincey.
Will and Tessa decide that the only way 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, while Tessa, Will and Jem spy on them. The three learn about Benedict's desire to control the Institute. Meanwhile, in the meeting, the Shadowhunters reluctantly agree to allow Tessa and Will to infiltrate de Quincey's party, while they will wait outside for a signal—another one of Henry's inventions.
At the party, Magnus seeks Will and Tessa and they discover mysterious manuscripts in the library, which contain scribblings that indicate towards the formation of a clockwork army. However, they are forced to join the vampires in another room before they can discuss the matter further. The room is set up to host one of de Quincey's 'performances'. As per the plan, Magnus is escorting Tessa out before the first drop of blood is drawn. However, the sacrificial lamb is revealed to be Nate and Tessa impulsively blows her cover to save him. Will summons the other Shadowhunters, who fight and kill most of the vampires. Will confronts de Quincey as the latter attacks Tessa—who was still in Camille's disguise—and Will bites him, mocking him and asking the vampire how it feels to be on the receiving end of one. Infuriated, de Quincey tries to kill him, but Tessa fires at him, compelling the vampire to escape, while 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, the Silent Brothers are summoned for Nate's treatment. Noticing Sophie's indignation, Tessa brings Holy Water for Will, to help annihilate the effects of the foreign blood in his body. However, they share a passionate kiss before Will ends it abruptly and pushes Tessa away. She leaves, hurt by his reaction, but not before noting how Will was continuously whispering a name—'Cecily'.
The next morning, Tessa encounters Jessamine taking care of Nate and Tessa instantly recognizes the fact that Jessamine wished to run away with Nate as he was a mundane. She is later summoned by Charlotte where she overhears the Shadowhunters discussing her brother's fate and she snaps when she hears Will talking indifferently about Nate.
Unaware of what happened in the attic, Jem tries to cheer Tessa up and takes her to his favorite place in London, the Blackfriars Bridge. She learns about Will's heritage before they are attacked by the Magister's clockwork army. Knowing that they are overpowered, they rush back to the Institute, and almost make it, 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, Jem calls for Tessa in his room, and he explains why he collapsed earlier, despite Will's protests that he not do so. When Jem was younger and living in China, a greater demon named Yanluo 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 its babies. Yanluo tortured him by constantly feeding him a demonic drug—yin fen—that caused him to hallucinate for days. By the time the Clave could step in and stop this abuse, but his parents had been killed and. His injuries were cured, however there was no remedy to his addiction. Jem admits that his body is now dependent on the drug and he has to take some of it every day, causing his skin, hair, and eyes to pale to a silver color, for without it, his body cannot function. He claims that he did not take any dose when he was out with Tessa, which was why he collapsed.He requested that she should not blame herself for his pain. 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".
Once Nate regains consciousness, he is interrogated by his sister and the London Shadowhunters. He informs Tessa of how he had come to London to bribe Mortmain into taking him to the Pandemonium Club. Mortmain, being indebted to help the son of Richard Gray, offered a job to Nate as well. Once Nate got into the Downworld club, he began gambling once again. Initially he made handsome money, but as he began losing, he was compelled to seek help from the "Magister", Alexei de Quincey. De Quincey demanded that Nate hand over his sister to him. Nate then wrote a letter to Tessa and called her to London. De Quincey had Nate imprisoned and when Tessa escaped, decided to punish her brother. Nate also reveals de Quincey's lair, the place where he was hiding, while planning to activate his clockwork army using a binding rune, which would infuse demonic energies into the automaton's body. He reveals that this ritual was supposed to take place on the night of the full moon.
Since it was the same night when de Quincey is supposed to strike, most of the Shadowhunters leave to kill de Quincey in his hideaway in Chelsea. Mortmain, the mundane who informed the Shadowhunters of de Quincey, visits the Institute to tell Will and Jem about the Dark sister who is trying to help the Magister in resurrecting his army and also told them about her location. They rush off to kill her, leaving Nate, Jessamine, and Tessa alone with Sophie, Agatha, and Thomas in the Institute.
While they are waiting anxiously for the others to return, Tessa and Nate have a word where he tells her of how the Magister called her "special" and compelled him to write her the letters that would bring her to London, ignoring his pleas.
Mortmain returns to the Institute, this time armed with the clockwork army. The automatons gain access to the Institute by using Jem's blood from the clockwork figure's hand, from the previous night and immediately kill Agatha. Mortmain reveals himself as the real Magister and discloses the truth about de Quincey's falsehood. Nate betrays them and reveals that he himself is 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 imitating Will's voice. When Mortmain threatens her, 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, knowing that Mortmain valued her life and would use her powers for ill-use, stabs herself in the heart and falls into the fountain.
Will and Jem go to destroy Mrs. Dark, and find that she is attempting to resurrect her sister using necromancy. They also discover a cat she wants to sacrifice for the ritual. When they confront her in the Pentagram that she is hiding in, Mrs Dark mocks them for falling for Mortmain and Nate's ploys. The duo then realize that it is indeed Mortmain who is the real Magister and Nate is unmasked.
Will rides back on Balios 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's death and after thanking him for everything that he has done, goes on to look for Tessa and the others. When 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 flees with the Pyxis, just before Charlotte and Henry come to help Jem finish of the automatons. Charlotte informs him that de Quincey had laughed at the Enclave for mistaking him as the Magister, and Benedict Lightwood then had him killed.
At the same time, Will finds Tessa and Mortmain in the Sanctuary; Tessa, bleeding to death near the fountain, and Mortmain, kneeling beside her. Will lunges at Mortmain but the latter disappears, leaving no trace behind him. Will breaks down and mourns Tessa's 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 attempted the trick with whilst living with The Dark Sisters; the dead woman's blood had poured down Tessa's chest, looking like she had wounded herself. Will embraces her and allows himself to feel vulnerable for once.
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 the latter accepts.
Tessa joyfully goes to Will wanting to have a serious relationship after he somewhat 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 barren. Tessa is horrified because this fact was unknown to her, 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 pendant, flies back to Tessa's arms.
Magnus Bane is temporarily residing in Camille Belcourt's house. Camille has gone undercover for some time, until Alexei's clan did not stop hunting for her. Archer, Camille's subjugate, tells Magnus that he had a visitor. Magnus enters the parlour, only to be met with a distraught Will Herondale, who begs Magnus for his help, which the latter seemingly obliges to.
Prologue: London, April 1878 & Southampton, May 1878
- 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.
- 10th Anniversary Special Edition: A special edition by Walker Books was released in November 2019 to commemorate the book's 10-year anniversary since its first release (released earlier so that it was released ahead of Chain of Gold), similar to the one released for City of Bones. As its exclusive bonus content it includes new art by Kathleen Jennings, portraits of the characters revealing their birthstones drawn by Cassandra Jean, as well as a list of their birth dates.
- The boxed Illumicrate edition includes a letter Tessa wrote during the events of the book as well as tarot card art by Tara Spruit.
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.
- "so we're releasing the 10th anniversary edition of Clockwork Angel ahead of schedule to give fans a chance to get re-reading before Chain of Gold!" Cassandra Clare on Tumblr
- Clockwork Angel 10th Anniversary Edition by Cassandra Clare (exclusive edition) - Illumicrate
- 'Mortal Instruments' Prequel Movie in Development (Exclusive)
- "Last time I talked to them about it they were discussing TV." Cassandra Clare on twitter