The Red Scrolls of Magic (the Eldest Curses, #1)

The first book in The Eldest Curses series follows Magnus Bane, a centuries-old warlock (an immortal being born from demon and human bloodlines, gifted with magic) and Alec Lightwood, his new boyfriend and a Shadowhunter (a warrior descended from angels who hunts demons). Their relationship is controversial: Shadowhunters, also called Nephilim, are governed by the Clave, a rigid institution that views Downworlders (warlocks, vampires, werewolves, and faeries) with suspicion. On their first romantic vacation in Paris, they are still in the early stages of their relationship.

Magnus plans an elaborate hot-air balloon dinner, but Alec spots demons on the rooftops below and leaps into action. They crash the balloon but survive, and the evening recovers with a moonlit walk and passionate kisses. Back at Magnus's apartment, they find Tessa Gray, Magnus's warlock friend of over a century, with alarming news. The Spiral Council, the closest thing warlocks have to a governing body, has demanded Magnus neutralize a demon-worshipping cult called the Crimson Hand. Once harmless, the cult has gained a powerful new leader and is killing faeries and mundanes (non-magical humans), working to summon a Greater Demon, one of the most powerful beings in Hell. Tessa shows Magnus a painting from the cult's Venice headquarters depicting its founder, called "the Great Poison," who is unmistakably Magnus. Magnus insists he cannot remember founding a cult, but privately recognizes that his memories of the relevant period have been magically erased. If he does not stop the cult, the Council will alert the Clave. Alec promises to help.

Searching his memories, Magnus finds evidence of erasure: a night of drinking with his late warlock friend Ragnor Fell, joking about starting a cult, followed by a three-year gap. At the Paris Shadow Market, an ancient Downworlder marketplace, a mundane informant named Johnny Rook, who possesses the Sight (the ability to perceive the hidden magical world), reveals the cult worships Asmodeus, a Prince of Hell. This horrifies Magnus, because Asmodeus is his own demon father, a fact he has never shared with Alec. Johnny provides the password to the cult's secret sanctum in Venice and names a former member, Mori Shu, who is fleeing. Meanwhile, Alec fights a mysterious cloaked warlock woman following Magnus. They travel to Venice by train, avoiding Portal travel (magical gateways the cult is monitoring).

On the Orient Express, demons attack. A Raum brood mother, a massive demon, seizes Magnus, and Alec fights across the speeding roof to rescue him but collapses from demon poison. The cloaked woman reappears, destroys the brood mother, and helps heal Alec. She introduces herself as Shinyun Jung, claiming the Crimson Hand killed people she loved. Magnus accepts her as an ally; Alec reluctantly agrees.

In Venice, the cult's former palazzo is hosting a Downworlder masked ball. The trio attends, hoping to find Mori Shu and the cult's hidden Chamber. Magnus's friend Catarina Loss, a warlock healer, warns that his relationship with a Shadowhunter endangers him. Another warlock, Hypatia Vex, tells Magnus never to reveal that Asmodeus is his father. Shinyun confesses she was a Crimson Hand member as a child, recruited and made to kill in the cult's name, leaving Magnus overwhelmed with guilt. Alec encounters Helen Blackthorn, a Shadowhunter with faerie heritage who suspects Magnus of leading the cult. Leon Verlac, a Shadowhunter from the Paris Institute whom Alec rescued during the balloon incident, vouches for Alec. The party is destroyed when a rival warlock triggers a magical battle that collapses the building, and Mori Shu is found murdered on the front steps.

Beneath the ruins, the trio discovers the cult's hidden Chamber and the Red Scrolls of Magic, the cult's sacred text. The book contains Magnus's humorous commandments, including instructions to care for warlock children, ending with the line "all roads lead to Rome." Driving to Rome, Magnus reveals his traumatic past: His mother died by suicide. His stepfather tried to drown him, and Magnus killed the man with uncontrolled fire magic. The Silent Brothers, a monastic order of Shadowhunters, took him in and taught him to control his powers. Alec tells Magnus that reading the Red Scrolls, he saw someone trying to help children, not someone doing evil.

In Rome, Alec visits the local Shadowhunter Institute, reuniting with his childhood friend Aline Penhallow and encountering Helen again, who has intelligence about a Crimson Hand meeting point. Shinyun lures Magnus to a bathhouse and secretly poisons his drink, neutralizing his magic. She sends Alec a false message directing him elsewhere. At the forest meeting point, Alec receives a call from Raphael Santiago, second-in-command of the New York vampire clan, revealing that Mori Shu's wounds match Shinyun's weapon, a Korean three-sided sword. Alec also realizes the "all roads lead to Rome" line was absent from a copy of the Red Scrolls his sister Isabelle Lightwood found in the New York archives, confirming the Venice version was altered as bait. Pillars of fire erupt around the Shadowhunters, revealed to be Cherufe, powerful fire demons. Alec, Helen, and Aline fight free and use a tracking rune, a magical mark that locates a person through a connected object, to find Magnus at a villa outside Rome.

Shinyun reveals herself as the cult's true leader, declaring herself the daughter of Asmodeus and planning to sacrifice Magnus to summon the Greater Demon. Powerless and imprisoned in a pentagram before hundreds of chanting cultists, Magnus undergoes a ritual that restores his stolen memories. He relives founding the joke cult and the horrifying moment Asmodeus himself appeared, drawn by worship in his name. The Greater Demon seized control of the cult and erased Magnus's memories. Magnus is relieved he was foolish rather than evil but deeply ashamed of the consequences.

Asmodeus manifests as a projection and offers Magnus a throne. Shinyun is devastated to learn Magnus is Asmodeus's actual son, meaning her belief that she was the demon's favored daughter was a lie. Magnus refuses, declaring his love for Alec. Asmodeus warns that if Alec learns who Magnus's father is, Asmodeus will kill Alec. When Magnus drops the sacrificial knife, Asmodeus offers Shinyun power if she kills Magnus. She attacks but hesitates, and an arrow strikes her arm: Alec has arrived.

Alec, Helen, and Aline fight toward the stage. The cultists have trapped Magnus and Shinyun in a larger pentagram, while Asmodeus creates dozens of illusory duplicates to prevent rescue. Alec identifies the real Magnus because one figure reached for a knife and let it go, an act of mercy only Magnus would perform. He grasps Magnus's hand through the pentagram's edge, and Alec's angelic strength flows into Magnus, restoring his magic. Magnus shatters the barrier. Asmodeus's projection fades, creating a destructive abyss, but Helen and Aline pull everyone to safety.

A cultist named Bernard claims to lead the Crimson Hand, clearing Magnus's name. The group keeps the full truth secret. Alec cuts Shinyun's bonds and lets her escape, honoring Magnus's wish for mercy. Helen and Aline's romantic connection blossoms, and Alec declares his intention to change the Clave's unjust laws from within. Magnus and Alec Portal home to Brooklyn, where they finally consummate their relationship. Magnus reflects that after centuries of wandering, he has found home in a person. In a final scene, Shinyun returns to a hidden house in Korea, where she has imprisoned Ragnor Fell, alive despite everyone believing he died in the recent war, in a cage in her cellar, declaring she has a new plan and that he will help her.