Clockwork Prince recap

London, 1878. Tessa Gray is living at the London Institute while the Clave gives Charlotte Branwell a fortnight to find the vanished inventor Axel Mortmain or forfeit the Institute to Benedict Lightwood. The search produces Mortmain's history rather than his address: he was the adopted mundane son of two warlocks killed in a Shadowhunter raid, and has spent his life building an automaton army to avenge them. Jessamine Lovelace is exposed as having fed information to Tessa's traitor brother Nate and is taken to the Silent City. Will Herondale, who has believed since he was twelve that a demon cursed everyone who loves him, forces that demon to admit it lied, and is freed just as Tessa accepts a proposal from his dying parabatai, Jem Carstairs. Benedict's claim on the Institute collapses when his demon pox and his dealings with Mortmain surface, and Charlotte holds her post after discovering that the Consul himself has been Mortmain's informant. Nate dies of his injuries in Tessa's arms, Mortmain remains at large, and Will's sister Cecily arrives at the Institute demanding to be trained.

Previously, in Clockwork Angel: in 1878 Tessa Gray sailed from New York to London to join her brother Nathaniel after her aunt's death. She was met instead by the Dark Sisters, two warlocks who imprisoned her and forced her to discover that she could Change, taking another person's shape by holding something of theirs and reaching their thoughts and memories. They told her she was being prepared for a man called the Magister, who meant to marry her. Will Herondale, a Shadowhunter of the London Institute, got her out, and she was taken into the Institute household: its head Charlotte Branwell and her inventor husband Henry, the resentful Jessamine Lovelace, the scarred maid Sophie, and Will's parabatai Jem Carstairs, kept alive by a demon drug that is also killing him. The hunt for the Magister led them to a vampire's house and to an army of clockwork automatons animated by bound demon energies. The Magister proved to be Axel Mortmain, a mundane industrialist with a private grudge against Shadowhunters and a plan that requires Tessa herself. Nathaniel had been working for him throughout and betrayed the Institute from inside; two of its household were killed in the attack. Mortmain escaped, telling Tessa he had arranged her birth and knew what she was. Tessa stayed on at the Institute with no family left, wearing the small clockwork angel her mother left her, which ticks like a heart.

The Clave's patience has run out. The Consul, Josiah Wayland, gives Charlotte a fortnight to find Mortmain or lose the Institute, and Benedict Lightwood, who has wanted it for years, is ready to take it. Benedict's sons Gideon and Gabriel are installed as training instructors for the women of the household, which everyone understands is also a way of watching Charlotte. Tessa, who has no family left and no standing among Shadowhunters, insists on being part of the search rather than kept out of it. Will is colder and more reckless than in the previous book and refuses to explain his nights away from the Institute to anyone, including Jem, whose illness is worsening and whose drug supply is becoming harder to obtain. The one lead available is Camille Belcourt, a vampire who was second to the clan leader the Shadowhunters destroyed; she claims to know something of Mortmain and will trade it, negotiating through the warlock Magnus Bane, for a pardon and the Institute's protection.

Camille's terms are agreed, and what she gives points the Institute north. Mortmain's history runs back to a pair of warlocks named Shade, who built mechanical creatures and raised a mundane boy as their son. Charlotte, Will and Tessa travel to York to see Aloysius Starkweather, the old and hostile former head of the York Institute, who led the raid that destroyed the Shades decades ago and kept records of it. Using an object from his collection Tessa Changes and lives through that raid from inside another person's memory: Shadowhunters killing the warlock household, and the boy they had raised surviving it. That boy was Axel Mortmain, and his war on the Nephilim is a revenge he has spent a lifetime preparing. Starkweather's family carries a private grief of its own, a granddaughter who died the first time she was Marked, which suggests his bloodline was not what the Clave believed. Meanwhile Will is pursuing something of his own with Magnus Bane's help, vanishing at night and refusing to say why, leaving Jem to cover for him.

Jessamine has been leaving the Institute at night in disguise. She is followed and caught: she has been meeting Nate Gray, who has promised her marriage and the ordinary mundane life she has always wanted, and she has been passing him what she learns at the Institute. Questioned by the Silent Brothers under the Mortal Sword, which compels the truth, she gives up what she knows and is taken to the Silent City, and the household learns that Mortmain's real object inside the Institute was the Pyxis, the sealed box of bound demon energies he needs to animate his automatons. Nate is taken into custody. Around this the household's private lives tighten: Sophie is drawn to Gideon Lightwood, who is increasingly ashamed of his father and says less than he knows; Jem's health continues to slip; and Will, still working with Magnus Bane, is hunting a specific demon for reasons he will not explain to anyone.

Jem tells Tessa that he loves her and asks her to marry him, knowing what his illness means, and she accepts; he gives her his mother's jade pendant. Will's private hunt is finally explained. When he was twelve he opened a Pyxis in his father's study and released a demon, Marbas, which told him that from then on anyone who loved him would die. His older sister died that same night. Believing it, he ran from his family to the Institute and has spent five years making himself unlovable on purpose, which is the whole of his cruelty toward Tessa and his distance from everyone else. With Magnus Bane's help he summons and binds Marbas, which admits there was never a curse at all: it had frightened a child with a lie and killed his sister to make the lie hold. Will comes back free to love and be loved for the first time since he was a boy, and finds Tessa engaged to his parabatai.

Will's long-mocked insistence that demon pox is real turns out to matter. Benedict Lightwood has the disease, contracted through years of consorting with demons, and Will and Magnus see the proof at a demon revel held at Benedict's own house. Gideon, who has broken with his father, supplies the rest: Benedict has been taking Mortmain's money, which is why he pushed so hard for the Institute. Faced with exposure, Benedict withdraws his claim; Gideon leaves for the Institute while Gabriel stays behind with their father. Charlotte's fortnight is almost spent and the investigation has produced a history rather than an address. Mortmain is a mundane raised by warlocks the Nephilim killed, he holds property under names that are not his, and he has consistently known Institute business that no outsider should know, which points at someone inside the Clave.

Mortmain reaches inside the Institute one last time: Nate Gray is fatally injured by one of the clockwork creatures and dies in Tessa's arms. Charlotte uncovers correspondence proving that the Consul, Josiah Wayland, has been supplying Mortmain with information from the Clave's highest office, confronts him, and keeps the Institute; Benedict Lightwood's claim collapses, Gideon settles at the Institute for good, and Sophie's feeling for him is returned. Charlotte tells Henry she is expecting a child. Tessa is engaged to Jem, who is dying and knows it. Will, freed from a curse that never existed, tells Tessa he loves her, learns he is too late, and chooses silence and his parabatai's happiness over his own. Mortmain remains at large with his automaton army, the stolen Pyxis and an unexplained use for Tessa, and the Clave's own leadership has been compromised. In the closing pages a girl arrives at the Institute door demanding to be trained as a Shadowhunter: Cecily, Will's younger sister, come to bring him home.

Mortmain's reach extends into the Institute itself: Nate Gray is fatally injured by one of the clockwork creatures and dies in Tessa's arms, leaving only fragments of what he knew. Charlotte uncovers proof that the Consul, Josiah Wayland, has been passing information to Mortmain from the Clave's highest office, confronts him with it, and keeps the Institute. Benedict Lightwood withdraws his claim rather than have his demon pox and his payments from Mortmain made public; his elder son Gideon leaves the family house for the Institute, where Sophie's regard for him is returned. Charlotte tells Henry that she is expecting a child. Jessamine remains in the Silent City. Tessa is engaged to Jem, who is dying and whose supply of the drug that sustains him is increasingly precarious. Will, having learned that the curse he built his life around never existed, tells Tessa he loves her, discovers he is too late, and says nothing further out of loyalty to his parabatai, so the three of them go on together with it unspoken. Mortmain is still free, with his automaton army, the Pyxis taken from the Institute, and an unexplained purpose for Tessa. The book closes with a girl at the Institute door: Cecily, Will's younger sister, come to take him home and refusing to leave without him.