The story takes place in Spain in the 17th century. Alatriste (Viggo Mortensen) is a nationally renowned army captain and the guardian of Balboa (Unax Ugalde). Alatriste hopes to train Balboa to be a real man as strong as himself, but Balboa falls in love with a dangerous woman named Angelica (Elena Anaya), which makes Alatriste worried because Angelica's father Luis (Jesús Castejón) and himself have had a grudge. Entrusted by the head of the Inquisition, Frey (Blanca Portillo), Alatriste and Luis accepted a very dangerous assassination mission. However, when carrying out the mission, Alatriste was impressed by the noble spirit of the assassination target and let the two go, which also brought trouble to himself.