The Lost Book of the White

The second book in The Eldest Curses series, set in the Shadowhunters universe, opens with a 2007 prologue in which Magnus Bane, a centuries-old warlock, visits his oldest friend Ragnor Fell in Idris, the homeland of the Shadowhunters, angelic warriors who protect humanity from demons. Ragnor reveals that Sammael, a Prince of Hell long believed dead, has returned and needs a demon realm as a power source. If Sammael regains full strength and reunites with his consort Lilith, the Mother of Demons, catastrophic war will follow. Ragnor plans to fake his death and disappear. Before leaving, he tells Magnus where to find the Book of the White, a powerful spell book.

Three years later, Magnus lives in Brooklyn with his Shadowhunter boyfriend Alec Lightwood and their adopted warlock infant Max. Shinyun Jung, a warlock whom Magnus and Alec previously encountered and released from custody, breaks into their apartment alongside Ragnor, who is alive but under Sammael's control. Shinyun stabs Magnus in the chest with the Svefnthorn, an ugly barbed iron spike that leaves a wound with wisps of scarlet flame. Magnus negotiates Max's return, and Alec shoots Shinyun with a bow, but she and Ragnor escape through a Portal, a magical gateway, taking the Book of the White.

Catarina Loss, a warlock nurse and Magnus's close friend, examines the wound and finds it harmful but not immediately dangerous. Alec uses a Tracking rune to determine Ragnor is in Shanghai. The next morning, reinforcements arrive: Jace Herondale (Alec's parabatai, or sworn warrior-brother), Clary Fairchild (Jace's girlfriend), Isabelle Lightwood (Alec's sister), and Simon Lovelace (Clary's parabatai). Simon recently Ascended to become a Shadowhunter, taking the surname of his closest Academy friend, George Lovelace, who died during the Ascension ritual. He identifies Sammael as the oldest Prince of Hell after Lucifer. Clary tells Magnus she had a dream of him as a chained demon with an X of red fire on his chest. After leaving Max with Alec's mother Maryse Lightwood at the Institute, the Shadowhunters' headquarters, they Portal to Shanghai, though the Portal malfunctions.

They follow Alec's Tracking rune to a demon-filled trap; Ragnor is not there. The next morning, while Alec takes the others to the Shanghai Institute, Shinyun finds Magnus at the hotel and stabs him with the Svefnthorn a second time. The thorn bypasses his wards because it is already part of his magic, and the wound now forms an X on his chest. Shinyun warns that a third wound will make Magnus Sammael's willing servant; refusing means the thorn's power will burn him alive.

At the Institute, the group meets Ke Yi Tian, a young local Shadowhunter. Shinyun attacks with a demon army from the forces of Yanluo, a Greater Demon who once ruled Diyu, a demon underworld, before the Ke family killed him in 1875. Magnus discovers the Svefnthorn has granted him the ability to fly. They retreat to Ke House, where they encounter Jem Carstairs, a member of the Ke family and a former Silent Brother (a Shadowhunter monk) now living as a mundane, or non-magical human. Jem reveals that both his wife Tessa Gray and Magnus are "eldest curses," the oldest living children of Princes of Hell. Tian explains that Yanluo once had a permanent Portal between Diyu and Shanghai; when he was killed, the Portal closed, but now his trapped demon forces are reappearing. That night, chains appear on Magnus's arms.

At the Sunlit Market in Shanghai, the group learns the Svefnthorn is made of black adamas, a substance corrupted by a demon realm, which binds a warlock to that realm's ruler. Tian introduces them to Jinfeng, his secret faerie girlfriend, whose relationship with him violates the Cold Peace, a punitive treaty imposed on faeries. Faerie weaponsmiths present Magnus and Alec with the Heibai Wuchang (Black and White Impermanence), two ancient swords forged from former gods of the dead. When Alec grasps his black sword, he has a vision of a monstrous Magnus and understands he must wield the sword of judgment if Magnus falls.

Ragnor and Shinyun open a massive Portal to Diyu at the Market, flooding the area with demons. Magnus channels his magic through both swords, levitates his friends through the Portal, catches Ragnor and Shinyun, and seals the Portal from the other side. Inside Diyu, a vast underworld, the group is scattered. They descend into Youdu, Diyu's capital. Tian unexpectedly appears, battered but alive. When Jiangshi (zombie-like demons) arrive to claim a soul, Isabelle volunteers so she can search for Simon.

They encounter Sammael, who appears deceptively mild. Sammael reveals Tian has been working for him, blackmailed through Tian's relationship with Jinfeng. Sammael departs. The group escapes by jumping off a bridge into the void and lands at a cathedral in Diyu's mirror of Shanghai. Shinyun, annoyed that Sammael has abandoned his war plans for a vendetta, leads them to Simon, whom Sammael captured because Simon once struck down Lilith while bearing the Mark of Cain. Isabelle bursts in riding a giant faerie tiger and frees Simon. Tian arrives, revealing he was a double agent forced into Sammael's service.

The reunited group rests; Simon breaks down over grief for George's death. Alec proposes using Clary's Alliance rune, which allows a Shadowhunter and a Downworlder, such as a warlock, to share power. Magnus sneaks away to a ruined temple where Ragnor guards the Book of the White. He calls upon the spirits within the swords, which merge into a single blade and draw the thorn's magic from Ragnor, freeing him. The swords vanish. Ragnor gives Magnus the Book of the White, and they return to find the cathedral under attack.

Sammael sends the other Shadowhunters into the Hell of the Pit of Fire and takes Magnus, Alec, Ragnor, and Shinyun to Avici, Diyu's deepest hell. His plan is to swap Shanghai with Diyu, generating enough demonic energy to break the wards preventing him from entering Earth. Shinyun threatens Alec's life unless Magnus accepts the third thorn. Alec seizes the Svefnthorn and drives it into his own chest. The Alliance rune allows him to survive and pull the thorn's power from Magnus, expelling it as a floating orb. Shinyun grabs the orb, absorbing the thorn power, and transforms into a Greater Demon. She turns on Sammael, declaring she will rule alone, and flees through a Portal, destabilizing Diyu. Sammael departs to find a new realm.

Magnus frees Ragnor, and they Portal to the Pit of Fire, where the Shadowhunters have organized a defense under Jace's command. They open a Portal back to Earth. Ragnor goes into hiding as "Shade," promising to stay in contact. Magnus entrusts the Book of the White to Catarina. The group returns to New York, where Max is safe. Jace announces he will run the Institute jointly with Clary. Magnus hesitates to hold Max, fearing the thorn has left him monstrous, but Alec and Catarina reassure him. That night, Magnus sings Max an Indonesian lullaby, and Max says "bapak," the word for father, for the first time.

In an epilogue, the Princes of Hell gather at Sammael's request. He admits his plans failed because he underestimated the strength of a group working together and proposes the Princes set aside their rivalries to cooperate. He concludes by announcing he wants to discuss Lucifer, implying a far larger demonic threat to come.