Porthos wakes up from his drunken birthday celebrations with no memory of the night before, and with a dead body by his side. After being unjustly sentenced to death, he is abducted to the dangerous Court of Miracles. In their investigation to prove his innocence, the Musketeers 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's too late.