Diego Alatriste is a swordsman in a dangerous and corrupt 17th Century Spain, where his services are requested to settle debts or restore a family's reputation. When wounded in battle during the Thirty Years' War, he is forced to retire from the army. Now he lives a relatively quiet life of a swordsman-for-hire in Madrid. When he is hired by the Holy Inquisition to kill two mysterious travelers, guests of the British ambassador, he knows he is in serious trouble.