Callie Hart’s dark fantasy romance novel Brimstone (2025) is the second installment in the Fae & Alchemy series, continuing the story that began in the #1 New York Times bestseller Quicksilver. The narrative picks up with Saeris Fane, who, after killing the vampire king Malcolm, has been transformed into a Fae-vampire hybrid and reluctantly crowned queen of the hostile Blood Court. Alongside her Fae warrior mate, Kingfisher, Saeris must navigate the treacherous politics of her new court and master her emergent Alchemical powers. Their efforts are complicated by the appearance of a supernatural plague known as “the rot,” which corrupts the land and creates monstrous, unkillable creatures, threatening the entire realm of Yvelia.

Known for dark romance and dark academia, Hart situates Brimstone firmly within the popular “romantasy” subgenre, blending high-stakes fantasy with a central fated-mate romance. The novel’s world is one of complex magical systems, warring supernatural factions, and morally ambiguous characters grappling with their identities. As Saeris and Kingfisher face external threats from the rot and political enemies like King Belikon, they explore themes of The Corrupting Nature of Power, The Hope for Redemption, and Sacrifice as the True Measure of Love and Loyalty.

This guide refers to the 2025 Forever First Hardcover Edition.

Content Warning: The source text and this guide feature depictions of graphic violence, sexual content, cursing, illness, death, physical abuse, and animal death.

Plot Summary

The Fae warrior Kingfisher, also known as Fisher, patrols Ammontraíeth, the palace of the vampire court, to protect his mate, Saeris. He tracks and fatally wounds a vampire, but not before the creature prophesies that the court will fall with Saeris inside it. Shortly after, the smuggler Carrion Swift, whose Fae nature and royal lineage were recently revealed when a lifelong glamor broke, rushes to Kingfisher with urgent news. A white fox is being chased by feeders—enslaved, feral vampires used as soldiers by the Blood Court and typically controlled through blood magic—across the dead fields of Sanasroth. Kingfisher recognizes the fox as Onyx, a creature precious to Saeris that they left in Kingfisher’s home of Cahlish for safety. Kingfisher and Carrion ride out on horseback and fight through dozens of feeders to rescue the fox. Upon returning to the Cogs, the city surrounding the palace, they meet Kingfisher’s friend, the warrior Lorreth, who is searching for their companion Foley, a Fae who was turned into a vampire a thousand years earlier. Kingfisher brings the gravely injured Onyx to Saeris. To spare her grief, he uses his finite healing magic to save the fox, completely depleting his own reserves of that power, a healing ability that does not regenerate.

The perspective shifts to Saeris, a new Fae-vampire hybrid, as she prepares for her coronation as Queen of the Blood Court. She was turned by her maker, Taladaius, one of the five Lords of Midnight, the ruling council of the Blood Court who govern vampire law and succession, to save her life after she killed the previous king, Malcolm. Her ascension is part of a plan to end the war between Fae and vampires. In her chambers, tensions between Kingfisher and Carrion escalate, prompting Taladaius to warn Kingfisher against showing any weakness or fear for Saeris’s safety before the hostile court. In the Hall of Tears, Saeris is confronted by the other Lords: Zovena, a cruel, beautiful vampire; Ereth, a zealot; Algat, an old witch; and the ancient, mysterious creature called the Hazrax. Zovena, who is later revealed to be Taladaius’s former love, challenges Saeris’s right to rule and demands she prove herself by feeding on blood. Kingfisher offers himself, and Saeris performs a feeding ritual that is intensely euphoric for both, satisfying the court’s demands. The court accepts this, but during the crowning, Ereth tries to assassinate Saeris. Kingfisher kills him instantly with his god sword, Nimerelle, an ancient, sentient weapon capable of killing otherwise immortal beings, while Taladaius uses his blood-boiling magic, a form of vampire magic that allows powerful vampires to control or destroy others through their blood, on Ereth’s followers. Saeris seizes the moment to issue her first magically binding royal edicts, forbidding any harm to come to her or her allies and decommissioning the feeder horde from warfare.

Kingfisher travels to the Fae war camp at Irrín, where he meets Renfis, known as Ren, and Lorreth. Their reunion is cut short when eight feeders attack, moving in unnatural unison. The Fae discover these “infected” feeders absorb their magic and cannot be killed by magic, silver, iron, fire, or even decapitation, continuing to move and attack even when dismembered. They are later revealed to be reanimated human corpses altered by a magical corruption known as the black rot. The battle results in 114 Fae deaths. Kingfisher and Lorreth bring the heads to Ammontraíeth, where Carrion identifies them as former humans from Zilvaren, Saeris’s home realm. They realize Madra, Zilvaren’s tyrannical queen, must be sending them through a quicksilver pool, a sentient liquid metal substance that functions as a portal between realms. Saeris senses another quicksilver pool within the palace.

Using the pool, Kingfisher and Saeris travel to Cahlish, where they consummate their mating bond, a magically recognized partnership known as a God Binding that links their power, emotions, and physical sensation. Kingfisher later explains he cannot marry her because he does not know his true name, a requirement for the Fae ceremony. The next day, they learn the rot has destroyed the camp at Irrín. At Cahlish, Saeris visits Kingfisher’s comatose half-sister, Everlayne. Everlayne’s father is the corrupt King Belikon. The spirit of Kingfisher’s deceased mother, the oracle Edina, possesses Everlayne to warn Saeris that her Alchemist runes will eventually kill her if they are not sealed. Edina instructs her to find a hidden book in the Cahlish library but to keep it a secret from Kingfisher. Convinced Madra is behind the attacks, Kingfisher and Carrion depart for Zilvaren to secure silver for magical relics and to rescue Saeris’s brother, Hayden. Meanwhile, in Ammontraíeth, Saeris is attacked in the library by a vampire who is revealed to be the long-lost Foley. He has been hiding there for centuries and agrees to help her understand her powers. Saeris then discovers Edina’s book, magically hidden within hundreds of paper “stargazer” birds. In Zilvaren, Kingfisher and Carrion are betrayed and led into a trap set by the scorpion demon, Joshin. They defeat it, bargaining for an anti-venom and a secret in exchange for its life. They find Hayden, who has been led to believe Kingfisher murdered Saeris because of Madra’s political propaganda. After they are ambushed by Madra’s Guardians, Kingfisher unleashes a massive wave of shadow magic and battles dozens of Guardians with Nimerelle, and they escape through a hidden quicksilver pool. When they return to Cahlish after the Zilvaren mission, Everlayne suffers another violent seizure and is possessed by a dark entity that speaks through her and warns that “the gate is open” (374).

At the Evenlight Ball in Ammontraíeth, Saeris follows Edina’s journal and appoints a reluctant Foley as the new Lord of Midnight. During the ball, Taladaius and the witch Iseabail enact a secret plan. They poison the wine with Iseabail’s blood, which is lethal to vampires due to her witch magic. All vampires present are given the choice to take the antidote and revert to Fae or refuse and die; some, like Zovena, refuse and are forced to take it, and Foley also forces Taladaius to drink the antidote. Kingfisher, Saeris, and their friends escape and return to Cahlish. Soon after, the rot reaches Cahlish, forcing a full evacuation to the satyr city of Inishtar. They arrive to find Inishtar under attack by human feeders from Zilvaren, confirming Madra can open portals at will. They fight off the attackers, but in the chaos, Kingfisher fails to emerge from the shadow gate and is declared missing. Saeris realizes she can enter a shared dreamscape, a magical mental realm entered through unconsciousness that allows two bonded individuals to find each other across distances. She has Danya knock her unconscious.

In the dreamscape, Saeris finds a catatonic Kingfisher in a rot-infected version of Cahlish. The Hazrax appears and, by calling in her one promised favor, transports her physical body to Kingfisher’s actual location in the Wicker Wood. There, she fights guards loyal to King Belikon and discovers Kingfisher physically imprisoned within a dryad tree, an “oubliette,” serving a life sentence for the destruction of Gillethrye. Belikon demands that Saeris swear an oath of servitude in exchange for Kingfisher’s life. Following instructions from Edina’s book, Saeris calls Kingfisher by his true name, Khydan Graystar Finvarra, which breaks Belikon’s magical hold and frees him. She then uses the Hazrax’s rune to undo the power of the true name, preventing Belikon from using it. Onyx is killed defending Saeris from an attack. Overcome with grief, Saeris uses her Alchemist magic and the Hazrax’s rune to resurrect the fox, consuming the rune’s power in the process. Kingfisher beheads the immortal Belikon, and they escape through shadow gates to the mountain city of Ajun Sky.

They find Renfis, who was magically summoned to Ajun as a Knight of Orrithian. He reveals that the black gate to the demon realm of Diaxis has reopened. They learn that brimstone, the only known substance that can stop the rot, can be sourced from Diaxis. Kingfisher confesses that Belikon forced him into that same gate as a child, which is how he returned with quicksilver in his eye. Kingfisher and Saeris resolve to enter the gate together.

Inside Diaxis, they are confronted by a dragon named Arissan, who accuses Kingfisher of murdering her child, the dragon slain at Ajun. They are taken prisoner and brought before two powerful beings, Crave and Githrand. Kingfisher unleashes his shadow magic, revealing his half-god status. He then confirms their shared parentage by demanding to see “our father,” Styx, Lord of Dragons, and declares he has come to make a trade for a dragon.