Written by Matthew Newman; Directed by Farhad Mann
A strange man attacks the palace, slaughtering the guards.
Meanwhile, Siroc shows the other Musketeers his latest invention: a metal detector. They receive news of the attack at the palace and rush off to help.
The attacker goes after Louis. He and Anne try to hide behind a curtain, but a fallen guard accidentally tears it down. Louis takes a sword and prepares to defend himself when the Musketeers arrive. Surprised that only one attacker could do so much damage, they argue a bit over which one of them could take him down. Jacqueline faces him by herself. The attacker calls himself Siegfried and his sword Notung, the invincible sword of Norse myth. Siegfried throws Jacqueline against the wall. She falls to the ground, momentarily stunned, and he prepares to deliver the final blow.
Ramon rushes in to save Jacqueline. He is badly wounded, but Jacqueline manages to kill Siegfried.
The royal doctor is sent to care for Ramon. He insists that bleeding is the cure, despite Siroc's protests.
Jacqueline prays that Ramon will heal. D'Artagnan tells her that the King will honor her as a hero.
After bleeding Ramon, the doctor declares that he has done all he could, leaving Ramon to Siroc's care.
In a public ceremony, Louis presents Jacqueline with Siegfried's sword, which the royal metallurgists believe is an ancient blade. An assassin attempts to kill Louis with a crossbow. Jacqueline deflects the crossbow bolt with her sword and chases after the assassin, eventually catching up to him and throwing the sword into his leg.
Jacqueline and Duval report about the assassin to Louis and Mazarin. Jacqueline declares that the assassin is a Spanish agent and must be working with others, while Duval warns her not to be hasty. Jacqueline believes that she's been granted a "special power," which she demonstrates by cutting a fly in half with her sword.
D'Artagnan and Siroc care for Ramon along with a monk, Br. Antoine. Jacqueline declines their invitation to sit with them, saying it would be pointless as she can't do anything to help and must spend her time searching for the Spanish agents.
D'Artagnan confronts Jacqueline about her callous attitude as she polishes the sword. He asks to see the sword, and she loudly refuses, saying that the sword is the only thing protecting France.
Jacqueline offers to devote all her attention to protect Louis. He appoints her His Majesty's Special Protector.
Jacqueline interrogates the assassin. He says that anyone could fire the next bolt — even a Musketeer. Jacqueline has him tortured for more information.
D'Artagnan visits Jacqueline in the palace at night. She says she feels that only her sword can protect the King and that she cannot trust anyone. He reassures her that she can trust him. She kisses him.
Ramon, delirious, warns Siroc that the sword has an evil power.
The sword glows, casting a magical light over Jacqueline and D'Artagnan as they kiss. She reaffirms her need to fight injustice. She tells him that the assassin died during the interrogation, calling it a necessary evil. He reacts with horror and disgust and leaves her.
Mazarin confronts Anne about the royal decrees Jacqueline has ordered. He says he's worried that the decrees will be unpopular and about Jacqueline's lack of experience, but Anne says that he's just worried that Jacqueline is too ambitious and Mazarin doesn't want to lose power.
Duval and D'Artagnan encounter some Cardinal's Guards in the Cafe Nouveau trying to arrest a Spanish woman and her father. They fight. Jacqueline walks in, breaks up the fight, and continues the arrest, as she has decreed that all Spaniards in Paris must be rounded up and investigated.
D'Artagnan rushes back to the garrison to find that Jacqueline is arresting Ramon, despite his injuries. They try to make her stop, but she says that she cannot make exceptions for her friends.
Br. Antoine visits Jacqueline in the palace and confronts her about arresting Ramon. He offers to pray to help her find guidance, but she says that her path is clear.
D'Artagnan and Siroc visit Ramon in the dungeons. They discover that Jacqueline has confiscated his metal detector and placed it at the entrance.
Jacqueline advises Louis to seize all lands owned by Spaniards without waiting for the investigations and trials to conclude. She also voices her suspicions of Mazarin — who, as an Italian, is not that different from a Spaniard.
Siroc creates a "non-metallic concussion device" — a bomb inside a watermelon shell — to get a weapon past the metal detector in the dungeons. In order to sneak past, D'Artagnan dresses Siroc up as a pregnant woman, Ramon's wife, and puts himself in a fake beard.
Mazarin complains to Bernard about Jacqueline usurping his authority. Bernard says that the sword seems to make Jacqueline invincible, and Mazarin plans to steal it.
D'Artagnan and Ramon convince the guards to let Ramon out of his cell to see his pregnant wife. The guards comply, but demand that Ramon kiss his "wife." Siroc drops the watermelon bomb, which creates a distraction to cover their escape.
Mazarin tries to sneak into Jacqueline's quarters to steal the sword, but accidentally catches her having a bath instead and realizes that she's a woman.
Jacqueline confronts D'Artagnan and Siroc about Ramon's escape; they deny all knowledge of it. She receives a message to see the King, and takes D'Artagnan and Siroc with her.
Mazarin reveals Jacqueline's disguise to Louis, taking off her fake goatee and showing her wanted poster. D'Artagnan tries to arrest her, but she draws her sword and accuses him of revealing her secret. They fight, and she accidentally kills him. With his last breath, he says that he loves her. Jacqueline seems to snap out of the sword's spell. She sees flashes of the events leading up to this, and wakes up on the floor to see herself kneeling next to her.
After a few moments, she wakes up in the same position where Siegfried left her at the beginning of the episode. The other Musketeers help her subdue Siegfried with no injuries. A tiny nun walks in and collects Siegfried — whose real name is Gunther — saying that he has delusions and has run off from the sanitarium. She gives the sword to Louis.
To reward Jacqueline for her bravery, Louis offers her anything she wants. Jacqueline asks for the sword, and — despite protests from the other Musketeers — throws it into a lake.
Louis dreams that the four Musketeers are all children who come to him for help with their tyrannical teacher. He is finally able to say the "all for one, one for all" motto without someone interrupting him. It seems he's just fallen asleep during his lessons, and his teacher roughly wakes him.