City of Ashes (2008) by Cassandra Clare is the second novel in the six-part Mortal Instruments series. The book follows 16-year-old Clary Fray, who has recently discovered that she is not an ordinary mortal, but a Shadowhunter, part of a group who saves the world from demons. In City of Bones (2007) the first book of the series, Clary also learned that she is the daughter of rogue Shadowhunter Valentine Morgenstern and that her romantic interest, Jace Wayland, may be her brother. Struggling with these emotional upheavals, Clary and Jace also have to stop Valentine, who is summoning an army of horrifying demons, killing Downworlder teenagers, and collecting the magical artifacts called the “Mortal Instruments” to change the world forever. When Valentine seizes their friends Simon and Maia, Clary and Jace have no choice but to meet their father in his demon ship and enter the battle of their lives. The novel explores themes of The Dynamics of Family Loyalty and Betrayal, The Struggle for Identity, and The Complicated Conflict Between Good and Evil.

The Mortal Instruments series is part of the larger Shadowhunter chronicles universe and remains hugely popular among both teen and adult readers. City of Ashes was voted one of the top books for adolescent readers by the American Library Association in 2009.

This guide uses the 2015 Walker Books Paperback edition.

Content Warning: The novel contains elements of horror and depictions of violence.

Plot Summary

Clary Fray is struggling with the recent discovery that Jace Wayland, the boy she loves, may be her biological brother. A string of ghastly murders sends shockwaves through the Shadowhunter society of New York City. When a teenage warlock (wizard) and fairy are found killed and drained of blood, the suspicion turns to vampires. However, it soon becomes clear that the person behind the murders is Clary and Jace’s father, Valentine Morgenstern, a disgraced Shadowhunter. Meanwhile, after the events of City of Bones, Jace is haunted by his connection to Valentine. Maryse Lightwood, his adopted mother, thinks he is Valentine’s spy. Jace has lived with the Lightwoods since Valentine abandoned him at age 10. Much to Jace’s horror, Maryse now asks Jace to leave the Institute, the home of the Lightwoods and all New York Shadowhunters.

Jace seeks shelter with Luke Garroway (formerly Lucian Graymark), a werewolf pack leader who has been a mentor to him and Clary. Clary has been living with Luke, because her mother Jocelyn is at Beth Israel hospital, asleep in a self-induced coma. Luke welcomes Jace but asks the teenager to argue his case before Maryse. At the Institute, Luke, Jace, and Clary learn the truth behind Maryse’s coldness: She turned Jace away to spare him a trial by Imogen Herondale, the Inquisitor. However, Jace agrees to the trial since he is keen to prove that he has nothing to do with Valentine’s agenda. Imogen imprisons Jace in the pitch-black cells of the underground Silent City, where monks guard Shadowhunter knowledge and relics.

Valentine invades the Silent City, brutally kills the monks, and seizes the Mortal Sword, one of the three Mortal Instruments, or sacred magical relics of the Shadowhunters. He drops in on Jace in the cells but refuses to free him. Later that night, Clary, with the help of Jace’s adopted siblings, Isabelle and Alec Lightwood, rescues Jace from the cell. Magnus Bane, the High Warlock of Brooklyn, takes Jace to his apartment so he can treat his injuries.

Magnus tells the group why Valentine wants the Mortal Sword: Valentine plans to heat and dowse the Sword four times in the blood of a different Downworlder (part-demonic creatures, such as vampires, werewolves, and warlocks) child to convert the Sword’s allegiance from angelic to demonic. Once the Sword is converted, Valentine can summon any demon he wants, and create an army to overthrow the governing body of the Shadowhunters. Valentine must be stopped before he gains unlimited power.

Isabelle tells the group that the Queen of the Seelie Court—the local queen of the Fey—has summoned the teenage Shadowhunters in connection with the murder of the Fey boy. Jace, Isabelle, Clary, and Clary’s mortal best friend Simon, visit the court. Much to Jace’s discomfort, Clary has been dating Simon, who is in love with her. Jace asks the group to conduct themselves very carefully at the Seelie Court, since Faeries are known to play tricks on people.

The meeting begins smoothly, with the Queen promising Jace help if he asks Valentine about the blood in his veins. However, at the last minute, the Queen tricks Clary into ingesting a drop of fairy drink, which means Clary now belongs to the Queen. Clary can only be released if she kisses whom her heart covets. Simon thinks this is him, but the Queen indicates Clary wants Jace. Jace kisses Clary, and the spell releases, proving that it is indeed Jace whom Clary desires. Simon leaves in despair. He visits the Vampire lair for answers, where he is bitten and nearly killed. Raphael, a vampire who is friends with the Shadowhunters, rescues Simon and brings him back to Luke’s place. The only way to save Simon is to bury him so he can rise as a vampire.

Simon turns into a vampire. Clary believes her kiss with Jace caused Simon’s fate and decides to avoid a romantic connection with Jace at all costs. Amid all this, demon activities are on the rise in the city, as demons are being drawn to Valentine and the Mortal Sword. When demons attack Luke and Maia, a teenage werewolf, Jace and Clary rush to the rescue. Clary draws an original rune that scares off the demons, much to Jace’s surprise. It becomes clear that Clary has the rare ability to create—rather than copy—runes, or sacred, protective marks. Shadowhunters etch runes on their skin to protect against demons and to enhance their abilities; almost all runes are from the Gray Book, the sacred compendium of Shadowhunter Marks. Clary’s ability to create runes is, thus, truly exceptional.

Keen to know Valentine’s plans, Jace obtains Valentine’s location from one of the demons who attacked Luke. He meets Valentine in a ship the older Shadowhunter is using to ferry demons from various dimensions. Jace learns that Valentine has summoned Agramon, a powerful demon who takes on the form of whatever one fears the most. Valentine’s agenda is not just to overthrow the Clave and seize power, but also to “purify” Shadowhunter society of Downworlders. Jace asks Valentine the Seelie Queen’s question, but Valentine does not answer. Instead, he suggests Jace join him in exchange for Valentine’s sparing the Lightwoods. Jace refuses to join Valentine, sparking Valentine’s fury. The enraged Valentine decides to expedite his plans. He needs the blood of two more Downworlders for his ritual, so he kidnaps Simon (now a vampire) and Maia (a werewolf).

The Inquisitor learns Jace met Valentine in secret and imprisons him again. Alec frees Jace, while Clary informs everyone of the kidnappings. The teenagers, Luke, and Magnus converge near the Brooklyn waterfront so they can save Simon and Maia, chained in Valentine’s ship floating on the East River. Jace sends a message of help to the Queen of the Seelie Court. Since he did pose her question to Valentine, he hopes she can keep her end of the bargain. Magnus bewitches Luke’s truck so it can sail close to Valentine’s ship. As the truck gets closer, demons start flying off the ship and attacking the Shadowhunters and their friends. A flying demon seizes Clary and carries her off to the ship. Clary meets Maia, who tells her Valentine has slit Simon’s throat and drained him of blood. Maia is next in line. Clary creates a rune to open a portal in the ship’s metal wall and helps Maia escape. Before Clary can leave, Valentine catches hold of her.

Jace, Luke, and the rest of the group swim toward the ship, looking for Clary. Alerted to the danger, the adult Shadowhunters land on the ship as well. A massive battle breaks out between the Shadowhunters and the demons. Imogen Herondale apologizes to Jace for not believing him and dies while saving Jace’s life. Jace rushes inside the ship to find Clary, runs into the dying Simon, and feeds Simon his blood to revive him. Jace and the revived Simon find Valentine and Clary.

As Jace distracts Valentine by arguing with him, Clary draws a rune to help them escape. However, her power explodes, and she creates a rune that tears the ship apart. Valentine flees with the Sword as the ship disintegrates. Water fairies, sent by the Seelie Queen, rescue all the Shadowhunters.

At the end of the novel, Jace promises to love Clary like a sister from now on, which leaves Clary with mixed feelings. A mysterious Shadowhunter called Madeline tells Clary she knows how to break the spell of sleep that Jocelyn has placed on herself, setting the stage for Clary’s quest in the next book of the series, City of Glass.