Rebecca has a friend of hers trying to decipher a secret code, behind the back of her superior. She is threatened with a scorpion in her bed, which she manages to kill. Phileas offers to help, but the codebreaker is killed under his protection by the mysterious Cavois. Cavois makes another attempt on Rebecca's life, which is thwarted by a bulletproof corset. Phileas tries to confront Cavois but is thwarted: Cavois leaves him for later. Meanwhile, Jules is meeting with his old friend Alexandre Dumas. It turns out he was a spy at one time, and created the code and hid the transcription code in his novel The Three Musketeers. Dumas is up to his ears in debt, in part because he is trying to build a machine, the Phoenix, based on designs by Cardinal Richelieu from 200 years earlier. The others meet up with Jules, and are forced to flee before Dumas' debtors. Passepartout inadvertently activates the time machine, and the four go back 200 years. As they step out to investigate, Passepartout inadvertently activates the time machine again, leaving the other three stranded. Worse, Rebecca is mistaken for an assassin and taken before Richelieu, who wants her to kill the king...

Stilled trapped in the time of the Three Musketeers, Rebecca is mistaken for Madame D'Urfe, an assassin hired to kill King Louis XIII. Jules and Phileas must persuade the Three Musketeers to reunite to rescue Rebecca, and save the King by defeating Richelieu. Of the Musketeers, Athos is dead and the other two are relucant, but are swayed to join. Porthos is a dead-ringer for Dumas in the 19th century. Adding further confusion, Richelieu is a twin for Fogg, Louis XIII for Jules, and D'Urfe for Rebecca. Apparently they have not just traveled in time, but into a parallel dimension of some sort. Rebecca plays along with the Cardinal, who is forced to kill the real Madame D'Urfe when she shows up so as to cover his tracks. Meanwhile, Passepartout works to discover the secret to the Phoenix to return all to their rightful place and time, aided by his own counterpart, a scientific genius. Rebecca fails to kill the King, and Richelieu hauls her away, then tries to have the King killed. Fogg, Jules, and the Musketeers break into the prison and a fight ensues. They rescue Louis, but Passepartout arrives, freezing time for everyone except his friends, who escape back to the 19th century. In the "present", they have the code. Fogg confronts the assassin Cavois, and they have a duel of "Russian Roulette" which Fogg wins.