The Book of Love

In the small coastal town of Lovesend, Massachusetts, Susannah Hand has spent nearly a year believing her older sister Laura Hand, their neighbor Daniel Knowe, and their acquaintance Mohammed "Mo" Gorch graduated early and left for a music conservatory in Ireland. In frustration, Susannah smashes Laura's Harmony Sovereign Marveltone acoustic guitar, and a splinter lodges in her heel. Overnight, the guitar mysteriously reassembles itself.

The truth is far stranger. Laura, Daniel, and Mo died on the night of Daniel's birthday, and one night they materialize in the music room of Lewis Latimer Public School, where Mr. Anabin, the school's music teacher, reconstitutes their bodies using magic. A fourth entity appears with them, a disoriented figure with no memory of its identity; Mo names it "Bowie," and Mr. Anabin fashions it a body. A massive white dog then appears and transforms into a terrifyingly beautiful man called Bogomil, who tells the teenagers they died, escaped his realm, and must return. Mr. Anabin proposes a game with trials: If the teens succeed, Bogomil will release them. Bogomil writes "2 RETURN / 2 REMAIN" on the blackboard and departs.

Mr. Anabin explains he has magically rewritten everyone's memories to create the Ireland cover story and gives the teens two tasks: remember how they died, and perform magic before their next meeting. On the drive home, he reveals to Mo that his grandmother, Maryanne Gorch, a famous romance novelist who wrote under the pen name Caitlynn Hightower, died of a heart attack while Mo was dead. Mo is devastated; Maryanne raised him since his mother's death and was his only family.

Back in their lives, the teens discover unsettling signs. Daniel realizes his body was imperfectly reconstructed, with one of his ears swapped for Laura's. Mo, in his grandmother's empty house, is comforted by Jenny Ping, Maryanne's secretary and now Mo's guardian. The teens create a list of goals: stay alive, figure out how they died, learn magic, and keep Susannah uninvolved. Their early attempts at magic fail.

Meanwhile, Susannah meets Thomas, a quiet stranger at her coffee shop who has secretly served a supernatural being named Malo Mogge for over 300 years. They hook up, and Malo Mogge picks Thomas up afterward. Bogomil visits Daniel, warning him of dangers and advising him to "beware the greedy moon."

At their next meeting, the teens still cannot perform magic. Bowie crashes through the window as a bleeding seagull, and Mo instinctively commands it to stop, causing Bowie to revert to human form: the group's first demonstration of magic. Mr. Anabin assigns a new task: bring him a birthday gift made through magic. Laura and Daniel visit the Cliff Hangar restaurant, where they encounter Malo Mogge. Laura sings for her, losing herself in the performance. That night, the restaurant's owner and cook vanish, turned into tigers by Malo Mogge.

Mo begins a relationship with Thomas, who reveals his history. Born in 1691 in Sweden, Thomas and his brother Kristofer were recruited by Bogomil for a ritual to replace himself and Mr. Anabin as guardians of Malo Mogge's door, a threshold between Life and Death through which Malo Mogge, an ancient goddess, feeds on the dead. The ritual failed, Kristofer died, and a magical key that shifts between forms, including cup, coin, knife, and guitar, was lost. Thomas entered Malo Mogge's service to hunt the woman who disrupted the ritual, who is now Bowie.

Laura's powers grow rapidly. She unconsciously repairs the ear swap with Daniel, compels a music store owner into giving her a steep discount, and discovers she can alter people's memories. When she finds Susannah talking to Bogomil, Laura makes Susannah believe the encounter was a sleepwalking dream. Daniel, by contrast, refuses to use magic, believing it will corrupt him.

For Mr. Anabin's birthday, Laura gives him the reassembled Harmony guitar, Mo animates every statue in Lovesend into a midnight parade, and Bowie implants a song into the dreams of every newborn in a neonatal intensive care unit. Mr. Anabin then assigns a final task: Each teen must discover a magical doppelganger he placed in their lives at resurrection, a parasitic companion feeding on their power, and send it away. Laura realizes her father, who seemingly returned after 12 years, was never real and sends him away. Mo discovers Jenny Ping is the construct and unmakes her. Daniel discovers that Carousel, his 10-year-old sister, is not real: The original baby Caroline died as an infant, and Mr. Anabin created Carousel from Daniel's magic. Daniel refuses to send her away.

Malo Mogge raises a massive temple from the ocean floor and seals Lovesend, declaring no one may leave until her key is found. Ruth Hand, Laura and Susannah's mother, is killed when she steps between Malo Mogge and Bowie to protect Bowie. Laura begs the goddess to resurrect Ruth, but Malo Mogge refuses and removes Laura's ability to grieve.

Susannah pulls the guitar splinter from her heel and recovers all her suppressed memories. She realizes her sister and friends were dead, not in Ireland, and that Laura has been manipulating her with magic. With Bowie's help, she learns the full history and discovers the Harmony guitar is Malo Mogge's lost key, with the splinter as its missing piece.

Malo Mogge arrives at Mo's house demanding the key. When Susannah tries to negotiate, Malo Mogge sends a tidal wave that destroys the Hands' house and Daniel's home. Carousel saves Daniel's family by transforming them into small stones and holding them in her beak while riding out the wave as a giant squid. Malo Mogge kills Daniel by shrinking and crushing him, but in Bogomil's realm, Bogomil chases Daniel as a wolf, driving him to escape back through the door into the living world.

Susannah hands over the reassembled key and the ritual begins, but she breaks off, declaring the key does not want to be returned, and tells Laura to smash the guitar. Daniel bursts back through the door as a rabbit, slamming into Malo Mogge. Bogomil bites her neck; Thomas betrays his mistress and pins her arm. Mo and Daniel drive broken guitar pieces into Malo Mogge's body, and Laura cuts her throat with a dart fashioned from Malo Mogge's own rib—a weapon Malo Mogge had given Thomas to use against Bowie, which Bowie had stolen from Thomas during their chase and secretly passed to Laura. Malo Mogge dies.

Laura descends into Bogomil's realm and consumes Malo Mogge's body and magic, becoming a goddess herself. The key takes human form as a girl called Harmony, who bonds with Carousel for a mortal lifespan, providing the magic Carousel needs to remain real. Susannah takes Bogomil's place as guardian on the Death side of the door, while Daniel takes Mr. Anabin's place on the Life side, at a permanent cost: They can never simultaneously face each other and speak. Bogomil and Anabin, freed after centuries, leave Lovesend together. Thomas pursues Bowie to a hospital where Bowie has transformed into one or all of nine newborns; unable to bring himself to harm the infants, Thomas walks away. Laura resolves to endure hunger rather than feed on the dead as Malo Mogge did. The band reunites occasionally, with Daniel turning his back to play bass, a consequence of his new role. Carousel rebuilds the family home with magic, her guitar bearing a sticker: "This Machine Kills Gods."