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.

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 highborn and enlightened woman, Ninon, who really gets under Athos' skin. The Musketeers are forced to put aside their animosity towards the Cardinal when his life is placed in danger, and rescue this extraordinary woman.