The Assassin's Curse

Christopher Rowe, a young apothecary's apprentice in 1665 London whose late master, Benedict Blackthorn, left him extensive knowledge of codes, poisons, and remedies, travels by carriage with his best friend Tom Bailey, a baker's son. They have been summoned without explanation by Baron Richard Ashcombe, the King's Warden, the royal officer responsible for the king's security. Their carriage bypasses Oxford and delivers them to a grand estate where King Charles II is hosting a lavish party. Charles, warm and jovial, praises both boys for past service, calling Tom "a true son of England." Christopher reunites with Sally, a friend now working as chambermaid to Lady Pemberton, who is with the royal Court.

That evening, Christopher wanders into the servants' quarters and discovers the estate's cellarman dead in the master's bedchamber, showing symptoms of poisoning. He realizes the wine now being served to guests is poisoned. Before he can act, a hooded assassin slips a cord around his throat. Tom arrives and fights the man off, pushing him through a window, but the assassin survives and escapes. Christopher, his voice damaged, cannot shout a warning. He staggers to a balcony overlooking the ballroom and hurls a wine bottle at the king in desperation. Lord Ashcombe reads Christopher's frantic gestures and shoots the glass from Charles's hand just before he drinks. Two guests and a servant who already consumed the wine die, but Christopher saves most others with emetics from his apothecary sash, a tool-laden garment inherited from Master Benedict.

A coded message sewn into the assassin's cloak, deciphered using the Atbash cipher (a simple letter-substitution system), reveals a plot not merely against Charles but against the entire French royal family. The poisoning was staged to look like an attack on Charles, but the true target was his sister Henrietta, the duchesse d'Orléans, who had been attending the party in secret. Charles insists on sending Christopher, Tom, and Sally to Paris as part of Henrietta's household to protect her. Christopher will pose as Lord Ashcombe's grandson, Tom as his personal guard, and Sally, who speaks fluent French inherited from her French father, as a noblewoman called Lady Grace.

During the two-week journey to Paris, Tom trains in swordsmanship under Sir William Leech, a retired sword master commissioned by Lord Ashcombe to accompany and train him. Christopher studies Master Benedict's notes on poisons and rereads the assassin's message obsessively, troubled by its final line: "Until the time."

In Paris, the group settles into the Palais-Royal, Henrietta's residence. Almost immediately, a venomous asp is found in the duchess's bedchamber. A chambermaid is bitten; Tom kills the snake. Christopher finds a hidden cage rigged with a glass rod beneath the bed, proving the snake was a deliberate trap meant for Henrietta. The snake's owner, Pierre Amyot, comte de Colmar, a fellow houseguest at the Palais-Royal, angrily confronts Christopher, but Christopher holds his ground.

A young nobleman named Simon Chastellain, another houseguest at the Palais-Royal, confronts Christopher at swordpoint after noticing his suspicious expertise. Recognizing Master Benedict's apothecary sash, Simon stands down and asks Christopher to visit his uncle, Marin Chastellain, an elderly man with severe dementia who once hosted Master Benedict in Paris. At Marin's home on the Île Notre-Dame, Christopher finds a captivating storyteller and encyclopedia of French conspiracies. When Christopher mentions "until the time," Marin identifies the phrase as part of Molay's curse. He recounts how Jacques de Molay, the last Grand Master of the Knights Templar (a powerful medieval military order), was burned at the stake in 1314 after Philippe IV of France arrested the order to seize their vast treasure. Dying, Molay cursed Philippe and Pope Clement to die within the year (both did) and declared the treasure would stay hidden "until the time no prince of the blood sits upon the throne." Christopher realizes the assassins seek to eliminate the entire French royal line to fulfill this curse and claim the treasure.

Christopher formulates a new strategy: Rather than guarding Henrietta against endless attacks, he will find the Templar treasure first, removing the assassins' motive. Marin provides a poem by Vincent Voiture that begins the treasure hunt, along with a Templar gold florin as proof. Sally, meanwhile, befriends the lonely comtesse de Colmar, Amyot's wife, learning that Amyot is deeply in debt from shady dealings, making him a possible suspect.

Following the poem's clues across Paris, Christopher, Tom, and Sally trace a path from the Pont Neuf, where Molay was executed, to Notre-Dame, where they find the word "ARCADIA" hidden on a statue. Father Bernard, the longtime priest at Saint Mary's, the Templars' former church, gives them a tour of the old Templar headquarters and its Great Tower. Christopher connects "Arcadia" to Nicolas Poussin's painting Les bergers d'Arcadie (The Arcadian Shepherds), which hangs in the Louvre. He and Tom stage a diversion to swap the original with a copy from Marin's collection. Dissolving the paint on the original canvas reveals a Vigenère cipher, a keyword-based code. Tom's insight about taking the clues literally helps Christopher decode it, yielding the message: "The key is the blessing and the curse."

The assassins strike back. A wasp nest is deliberately placed near Henrietta's infant son, who is deathly allergic to stings; a nursemaid dies saving the child. Then a forged letter in a perfect copy of Christopher's handwriting lures Sally to Notre-Dame, where the assassin throws her unconscious body from the bell tower. Sally's grandmother's Saint Christopher medallion, a gift received during a visit to her estranged French family, catches on a gargoyle and suspends her in midair. Tom leans over the edge while Christopher holds his legs; the chain snaps, but Tom catches Sally by her collar. She survives but requires surgery for a severe head wound.

While praying over Sally, Christopher asks the crucial question: Why did the assassins keep him alive? He realizes they needed him to solve the riddles, and someone in Marin's household was reporting his progress. He identifies Rémi, Marin's head servant, as the spy. Christopher deduces from the treasure map that the hoard never left Paris; the five Templar knights who escaped were decoys, and the treasure lies hidden beneath the Great Tower.

Christopher devises a trap. He sends Tom to hide inside the Tower overnight, then walks there alone at dawn, allowing the assassins to follow. He rigs his equipment with quills filled with urare, a paralyzing poison from South America. Two assassins confront him in the dungeon and force him to solve the final riddle: A Templar florin serves as a literal key, unlocking a passage to a vast cavern filled with gold, silver, and priceless artifacts. Christopher whistles for Tom, who defeats the enforcer in a sword fight, the man weakened by the poison. The second assassin falls into a pit and, dying, names her mistress as the comtesse de Colmar.

Father Bernard arrives, revealing himself as a Templar guardian. The treasure hunt, he explains, serves as a test to recruit members and identify threats. He asks Christopher to return the treasure quietly, promising a letter that will neutralize the danger to the royal family. Christopher agrees. The Templars orchestrate the comtesse's arrest, but she is found dead in the Bastille before trial, apparently poisoned.

Sally awakens with significant memory loss and diminished strength in her left hand. Marin dies peacefully in his sleep, believing Master Benedict found the treasure. A letter arrives for Christopher in a perfect forgery of his own handwriting, signed by "the Raven," who claims to have poisoned Marin and reveals a long enmity with Master Benedict. The Raven promises to strip away everything Christopher loves before coming for him, setting the stage for future conflict.