When a Spanish general, Tariq Alaman, offers to hand over the formula of a unique and deadly gunpowder in exchange for help rescuing his kidnapped daughter, the Musketeers find themselves tangled in a complex web of political trades with the Spanish. Their mission is further complicated when Porthos is captured by Spanish agents.

Meanwhile, when the dauphin becomes seriously ill, Constance takes matters into her own hands and risks everything to save his life. Show less