Athos, Porthos and Aramis are sent by Captain Treville to locate a missing musketeer carrying important letters on behalf of King Louis. Cardinal Richelieu has plans to increase his political power and wants to sabotage the reputation of the musketeers. D'Artagnan leaves his family farm in Gascony to Paris to petition the king, but his peaceful plans end up being turned upside down after he is forced to find the Musketeers and seek vengeance for the shocking hug of a loved one.
Notorious criminal Vadim seeks to make life unbearable for the authorities that have imprisoned him. When he engineers a full-scale riot, it falls to the Musketeers to protect those whom he seeks to destroy. Will the Musketeers discover his plan in time and stop him from endangering the monarchy? And can the inexperienced d'Artagnan prove he is worthy of becoming a Musketeer, or do his loyalties lie elsewhere.
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. Will he overcome his demons and help the Musketeers safely return to Paris, or will Bonnaire's enemies get the better of them?.
When Aramis's old friend Marsac, a former musketeer, 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. Despite their misgivings, will the musketeers help and can they prevent Marsac exacting his own revenge?.
Porthos wakes up from his drunken birthday celebrations with no memory of the night before. This would not be unusual, but for the dead body by his side... After being unjustly sentenced to death, he is abducted to the dangerous Court of Miracles, the streets of his childhood. In order to save him, the Musketeers must prove his innocence. Their investigations 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 is 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. Meanwhile, 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 while 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, Ninon, who really gets under Athos's skin. 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 hug 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 between them to settle which one is stronger once and for all. D'Artagnan is determined to be chosen to fight so that he can prove himself worthy to be a Musketeer. But first he has to learn to control his impetuous nature and to fight with his head, not his heart.
Queen Anne's taking of the waters is cut short when her life is put in mortal danger. Meanwhile, 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. Under siege and fearful for their lives, the Mother Superior and nuns help the Musketeers to defend the convent, but what will they do once they run out of ammunition?.
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. D'Artagnan is forced to do the unthinkable and seeks Milady's help. The Cardinal, fearful the Musketeers will prove he masterminded the attempt on the Queen's life, compels Milady to hug 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. Can the Musketeers restore their team and bring Milady and the Cardinal to justice? Or will Milady finally wreak her revenge?.