The Poisoned King

Katherine Rundell’s The Poisoned King (2025) is the second book in the Impossible Creatures young adult fantasy series. The narrative follows two protagonists whose fates become intertwined: Christopher Forrester, a boy from London, is summoned back to the magical Glimouria Archipelago to investigate a mysterious ailment that is killing the realm’s dragons. At the same time, Princess Anya Argen’s life is shattered when her grandfather is murdered, and her father is framed for the crime, forcing her to flee a conspiracy orchestrated by her ruthless uncle. Together, they must uncover a plot that threatens the stability of the entire Archipelago. The novel explores themes of The Moral Crossroads Between Vengeance and Justice, The Sacred Interdependence of Humans and the Natural World, and The Moral Imperative to Challenge Corrupt Authority.

Katherine Rundell is an acclaimed British author, known for her award-winning fiction for children and young adults. The Explorer (2017) won the Costa Children’s Book Award, and Rooftoppers (2013) received the Waterstones Children’s Book Prize. The first novel in this series, Impossible Creatures, was a number-one bestseller in the United Kingdom and was named the 2023 Waterstones Book of the Year.

This guide is based on the 2025 Alfred A. Knopf edition.

Content Warning: The source text and this guide contain depictions of graphic violence, animal cruelty and death, and illness or death.

Plot Summary

Christopher Forrester wakes in his London bedroom to find Jacques, a tiny dragon, chewing on his face. Jacques reveals that dragons across the Glimouria Archipelago are dying from a mysterious illness. Sarkany, a great red-winged dragon, has sent Jacques to summon Christopher back to the magical realm. She believes his position as an outsider from the Outerlands makes him the perfect person to investigate. Christopher leaves a note for his father and travels to Scotland, where his grandfather, Frank, is the guardian of a portal, or “waybetween,” to the Archipelago.

Christopher enters the magical realm of the Archipelago by plunging into a lake. He is met by a sphinx named Naravirala. To gain her assistance, he solves a riddle. Naravirala then tells him of a prophecy about a child in mortal danger, connected to both Christopher and the dragons. She gives him a sword forged from dragon obsidian, and they fly off together.

On the southern island of Dousha, Princess Anya Argen rescues a royal gagana egg after a guard kills its mother, Felin. Anya was raised in the forest by her father, Argus, the king’s heir, and shares a deep bond with the gaganas, especially her companion Gallia. A year prior, she was forced to move to Argen Castle after spitting at her uncle, Claude, during a formal event. Back in her room, the rescued egg hatches, and Anya names the chick Koo. That evening, during the annual Argen Ball, King Halam is poisoned in his chamber.

At the ball, Argus arrives late, explaining he was lured to an empty library by a false message. The king’s death is announced, and the Poison Flock, firebirds trained to detect poison, are brought in to search the guests. A firebird finds a vial of the poison in Argus’s pocket, which Anya later realizes Claude must have planted when he embraced his brother. Argus is arrested for murdering the king.

Determined to prove her father’s innocence, Anya confronts her uncle Claude, now the regent, but he denies her request to see her father. During their meeting, she steals a small black book that he tries to hide. Using a secret passage, Anya enters her grandfather’s chamber and finds a pair of Claude’s signature white gloves, stained with poison, hidden in the chimney. Just then, Claude enters the room, forcing Anya to hide on the balcony. She watches as he burns the gloves, destroying the evidence of his guilt.

Claude arranges for Anya to be sent to a boarding school, but it is a trap. The soldiers escorting her take her into the forest to murder her. Anya fights back, aided by her flock of gaganas, and flees. She is cornered at a lake just as Naravirala and Christopher arrive. The sphinx attacks and disarms the soldiers, and Christopher pulls Anya onto Naravirala’s back. They escape into the sky.

Anya recognizes Christopher as the guardian mentioned in mermaids’ songs, and he explains his mission to help the dying dragons. They decide to seek help from his friends, Fidens Nighthand and Irian Guinne, on the islet of Glimt. They arrive at a palace that Nighthand and Irian have transformed into a refuge for magical creatures, where they meet a ratatoska named Ratwin.

Naravirala is forced to depart when she learns that a sphinx has been killed. Anya and Christopher travel to the dragon caves on Edem, where they are attacked by a blind dragon named Arach. To get past him, they ride on the backs of cave cattle. Inside, they discover Sarkany and her entire clan dead. Arach is the sole, dying survivor. Anya recognizes the scent of poison in the dragons’ water source. She deduces that Claude poisoned them and stole their gold to fund his growing army of mercenaries. Now pacified, Arach identifies Anya’s necklace, a gift from her late mother, as a “loquillan,” a magical artifact that can show the user a vision of their desired future.

Back at Glimt, writing appears on the loquillan, but it is in an unknown script. Following Ratwin’s lead, they search for the palace’s lost library. Anya uses rascovnic, a magical herb from her father, to open a secret door. The library is guarded by a harpy named Aellope. To borrow a notebook, Anya trades the black book she stole from Claude. Aellope recognizes it as a banished book of poisons. Jacques translates its content, revealing a recipe for dragonsbane. The recipe requires the blood of a newborn gagana, explaining the attempt to steal Koo’s egg. Jacques then discovers a recipe for an antidote. Meri, a mouse librarian, translates the runes on Anya’s loquillan, which suggest its powers can be unlocked with 12 pearls. While Anya unsuccessfully tries to activate the loquillan with pearls, the others prepare a batch of the antidote.

The next day, Irian and Nighthand leave on an urgent quest. A horned manticore sent by Claude attacks Anya and Christopher. They fight it off, discovering it is already dying from having eaten a poisoned dragon. They give it the antidote in exchange for information. The manticore reveals that Argus’s trial was expedited, and he will be executed in two days. The antidote works, but the manticore attacks them. Working together, Anya and Christopher kill it. Realizing she cannot enter the castle alive, Anya devises a desperate plan.

Anya and Christopher sail back to Dousha, stopping at Edem to give Arach the antidote. On Dousha, they are ambushed by guards, but winged unicorns summoned by Christopher intervene. They separate: Christopher goes to find the Poison Flock, while Anya rides a unicorn to the castle, where she is greeted by her uncle. In his study, Claude gives Anya a goblet of poisoned cordial. Jacques creates a diversion, and Anya splashes some of the poison onto Claude before secretly taking the antidote. She drinks the poison and collapses, appearing to die.

Twelve hours later, at Anya’s funeral, Christopher bursts in and accuses Claude of murder. He summons the Poison Flock, which swarm Claude, proving the accusation. Koo pecks Anya’s cheek, drawing blood, which revives her. The guards turn on Claude, and a healed Arach smashes through the wall to confront him.

Anya tells Arach she wants to kill Claude herself. She holds her sword to Claude’s throat, but her tears activate the loquillan. She sees a vision of a future where killing her uncle has turned her into a cruel queen, poisoned by her own hatred. Rejecting this future, Anya spares Claude’s life, has him arrested, and renounces the throne.

Anya replaces Dousha’s monarchy with a new government of humans and creatures. She and her father move to Glimt, where Christopher joins them. Irian and Nighthand reveal their quest was successful: they have confirmed that the new Immortal is a baby boy named Teren. The baby’s mother brings Teren to Glimt, where he recognizes Christopher.

After escaping prison, Claude poisons another dragon clan and steals their gold. However, the dragons have already taken the antidote sent by Anya and Christopher. Feigning death, the dragons then incinerate Claude, leaving a pool of molten gold.