After so many secrets and so much death, the riddles surrounding Lia's murder are solved, and D'Eon is finally able to give his sister peace.
D'Eon gains entrance to the King's chambers, but it Lia who confronts the murderous royal with accusations and explosive questions.
With Teillagory fallen, the Duke of Orleans attempts to flee. Meanwhile, Queen Marie is in grave danger. Sensing this, she asks a very important request of Robin.
D'Eon is taken to the mansion of the Duke of Orleans, while Robin formulates a plan to rescue him. But even if he gains his freedom, he must still get past Teillagory.
Durand's written confession surfaces, setting off a chain of events that reaches all the way up to the throne. Meanwhile, D'Eon returns to France - where the Duke of Orleans waits and betrayal is exposed.
With the Psalms in his possession, Durand attempts to reach France in order to avoid killing his allies. When his ambitions are foiled, he finds himself facing a grim fate.
Lia's angry recitation of the Psalms puts an end to the attacking monks, but it also threatens her allies. Meanwhile, Madame de Pompadour discovers an impending threat to the nation of France.
The Four Musketeers depart for Medmenham Abbey, unaware that sinister forces are already there and waiting to strike.
D'Eon goes to Queen Mary in hopes of securing the captured Durand's freedom, but finds that the Mary before him isn't the Mary he expected.
Durand is ordered by the King to execute D'Eon and anyone within his party who has read the Royal Psalms. Disheartened by the command, Durand makes a risky move.
The Four Musketeers succeed in stealing Wood's documents, but as they browse the purloined materials, Robin's hand is stricken by a strange curse.
The Four Musketeers arrive in London and make their way to a party thrown by England's Queen and King. The group isn't interested in revelry - there are documents to be stolen.
Vorontsov falls in the battle with D'Eon - though it is someone other than D'Eon who deals the final blow. With one adversary down, the Four Musketeers depart for London in pursuit of another.
Pyotr ascends to the position of Emperor following Elizabeta's demise, but his rule could be short-lived. With the assistance of the Four Musketeers, Ekaterina makes her move to claim the throne.
The battle between D'Eon and Vorontsov ends when a building collapses around them. Regardless, those plotting to assassinate Empress Elizabeta move forward with their plan.
D'Eon finds Empress Elizabeta to be a willing ally, due to her past friendship with Lia. Permission to arrest Vorontsov is granted - but first an attempt to kill the Empress must be thwarted.
The Four Musketeers reach their destination of St. Petersburg, but before their work in Russia can begin, they must gain entrance to a masquerade ball and garner the permission of Empress Elizabeta.
During the trip to Russia, the Four Musketeers register at an inn using false identities. Unfortunately, the sudden appearance of familiar enemies means rest and relaxation must wait.
After the King himself tasks the Four Musketeers with a mission, D'Eon seeks answers from Queen Marie about the fate of his sister's wandering soul.
D'Eon and Anna's day together is cut short when D' Eon spies Vorontsov. Meanwhile, King Louis offers a stern warning to the Duke of Orleans.
As the Duke of Orleans begins plotting the demise of the Four Musketeers, D'Eon learns the circumstances surrounding his sister's death.
The Four Musketeers manage to defeat the Gargoyles, but the man behind the beasts' actions escapes. When D'Eon and Teillagory give chase, they discover a shocking conspiracy.
D'Eon wakes with no memories of the chaos that erupted following his possession by Lia's soul. He soon finds himself on the run and in serious danger - until Durand steps in.
D'Eon joins the French secret police in hopes of finding the party responsible for the murder of his sister, Lia. Before long, he learns things are more sinister than they seem.