Frankreich, 1630. Der junge D’Artagnan und sein Vater werden in einem Landgasthof von einer Bande Maskierter überfallen, die sich als Musketiere ausgeben. Zwar kann der furchtlose D’Artagnan die Angreifer in die Flucht schlagen, doch sein Vater wird getötet – von einem Banditen, der sich selbst Athos nannte. In Wahrheit aber stecken hinter dem Mord die Männer des intriganten Kardinals Richelieu, der den König gegen die Musketiere aufhetzen will. Die Intrige scheint zu funktionieren: Athos soll für seine vermeintliche Tat hingerichtet werden. Seinen Freunden Aramis und Porthos bleibt nicht viel Zeit: Mit schlagkräftiger Unterstützung von D’Artagnan versuchen sie, den wahren Mörder zu finden.
Weil er sich auf ein illegales Duell eingelassen hat, wird D’Artagnan verhaftet und eingekerkert. Seine Freunde Athos, Aramis und Porthos ziehen sich die Verachtung der anderen Musketiere zu, weil sie bei der Verhaftung nicht einschritten und damit gegen den Leitspruch „Einer für alle, alle für einen“ verstießen. Doch in Wahrheit war die Verhaftung nur eine Finte: D’Artagnan soll im Kerker das Vertrauen des Anarchisten Vadim gewinnen, der große Mengen an Schießpulver versteckt hält. In einer spektakulären Aktion können die beiden aus dem Gefängnis flüchten. Aber D’Artagnan muss auf der Hut sein: Vadims brutaler Handlanger Felix misstraut ihm und wartet nur auf einen Grund, um ihn zu töten. Vadim hingegen weiht seinen neuen Gefährten in seinen Plan ein: Er will einen Sprengstoffanschlag auf den König und die Königin verüben. Doch das ist nicht die ganze Wahrheit.
The Musketeers are dispatched to Le Havre to collect the infamous merchant trader and explorer, Bonnaire and bring him back to Paris to be reprimanded for breaking France's trade treaty. This straightforward mission soon descends into a treacherous battle, as they must defeat Bonnaire's surprising number of enemies. Athos is forced to confront his past, which threatens to engulf him.
When Aramis's old friend and former musketeer, Marsac, unexpectedly returns to Paris, the musketeers are thrown into turmoil, fully aware that they should report him for desertion. His appearance coincides with the royal visit of the King's beloved sister and her husband, the Duke of Savoy, whom the musketeers must protect. Marsac believes he finally knows the truth behind the infamous massacre which killed his troop, and wants Aramis's help to prove it.
Porthos wakes up from his drunken birthday celebrations with no memory of the night before, and with a dead body by his side. After being unjustly sentenced to death, he is abducted to the dangerous Court of Miracles. In their investigation to prove his innocence, the Musketeers uncover a tangled web of divided loyalties and greed, and they risk their lives to infiltrate the unruly slums of the Court of Miracles before it's too late.
Aramis and D’Artagnan are thwarted in their task to transport a young woman and her baby from a village outside Paris to the palace when armed men abduct her baby. They must find out who she is exactly and why anyone would go to such lengths to kidnap her son. The King’s royal hunting party is disrupted by the sudden appearance of Louis’ banished mother, Marie de Medici, seeking royal protection from an unknown assassin. The Musketeers must fight to protect both mother and baby whilst also loyally defending the throne.
Following the tragic death of a young girl underneath the royal carriage, The Musketeers’ investigations into her missing friend lead them into the world of a high-born and enlightened woman. The Musketeers are forced to put aside their animosity towards the Cardinal when his life is placed in danger and they must rescue this extraordinary woman.
The Musketeers are tasked with bringing the fearsome Labarge, a regional intendant under arrest for the murder of two Musketeers, to Paris. The Red Guards, resentful of the Musketeers' handling of him, initiate a vicious fight between the two regiments. Fed up with the disruptive rivalry between the Musketeers and the Red Guards, the King calls a contest to prove which group is the stronger. D'Artagnan is determined to be chosen to fight so that he can prove himself worthy to be a Musketeer.
Queen Anne’s taking of the waters is cut short when her life is put in mortal danger. King Louis dines with wealthy German banker Count Mellendorf, who is looking for a French match for his beautiful daughter. As the Musketeers try to spirit Anne back to Paris, they’re forced to seek refuge in a fortified convent, where Aramis comes face to face with his past.
Athos takes a woman hostage in the square and the Musketeers are amazed to discover he is threatening none other than Milady. Athos is furious when he finds out that D’Artagnan knows her, testing their friendship to its limits. The Cardinal, fearful the Musketeers will prove he masterminded the attempt on the Queen’s life, compels Milady to kill them by any means. Milady has no choice but to revisit her dark past and in doing so puts Constance into danger. The Musketeers must use all their wits and courage to outsmart her and save Constance.
The Musketeers must rescue a French general from an impenetrable Spanish prison.
D'Artagnan must protect King Louis when a notorious criminal kidnaps them both.
The Musketeers help rescue an enemy's daughter in exchange for a deadly gunpowder formula.
A woman claims to have visions from God which instruct her to start a war with Spain.
Athos must confront his past to protect the people he left behind.
An astronomer gathers the royal party to see an eclipse, but events take a dramatic turn.
The King’s cousin is ambushed while under Musketeer escort as she travels from Mantua to Sweden to make a political marriage that will be advantageous to France. The Musketeers must quickly discover who is targeting her to keep both her and the alliance between countries protected. However it emerges that other important figures at Court also appear to be in danger. Who is the killer and could he already be inside the Palace walls?
Porthos uncovers the truth about his parentage and demands answers from his new found father. As he learns more about his past, Porthos questions his place in the Musketeers regiment. However the Musketeers have suspicions about Porthos’ new family, wondering whether he should trust them. Can they save Porthos from the dangers that lie ahead and where do his true loyalties lie?
The Musketeers must put their lives on the line when the Queen is accused of treason. They have no choice but to steal her away from the Palace to safety, while they search for evidence to prove that Rochefort is a Spanish spy. However it soon transpires that nobody is safe from Rochefort’s grasp, not even the King, with devastating consequences.
The Musketeers must risk everything to save France from Rochefort’s treacherous plan. While Porthos seeks to lure the Spanish spy-master to Paris to prove Rochefort’s betrayal to the King, Athos and d’Artagnan must save Constance from certain death. But will they be able to protect Aramis and the Queen before Rochefort gets to them? The fate of France and their closest comrades lies in the Musketeers’ hands.