King Louis demands to experience the life of his carefree subjects, but his night of fun quickly comes to an end when he and d'Artagnan are mistaken for commoners and kidnapped by the notorious criminal Lemaitre to be sold to Spain as slaves.

The musketeers must find and rescue d'Artagnan and the king. Can they save Louis from mortal danger and will they return him to the palace in time for the dauphin's christening?

Meanwhile Rochefort uses the king's absence to become closer to Queen Anne.

The Musketeers investigate Emilie of Duras, a woman claiming to have visions from God which instruct her to lead her thousands of followers into war with Spain. As word of Emilie's visions triggers violent anti-Spanish riots, Aramis is sent to discredit her before she pushes France into an ill-timed war with Spain.

Meanwhile Rochefort continues to clash with Spanish Ambassador Perales. He resorts to blackmail and murder to resolve the problem.