In 16th-century England, Solomon Kane is a ruthlessly efficient captain of a privateer ship, plundering his way across the seas in the name of England. Possessing a brutal and selfish nature, his insatiable quest for riches leads him to a dark and evil place where his actions result in the encounter with the Devil's Reaper. The Reaper claims that Kane's soul is forfeit to hell for his life of sin. Shaken to his core by this realization, Kane manages to escape, but the encounter transforms him. Vowing to renounce violence and atone for his past, he takes up residence in a monastery, seeking peace and redemption.

However, the world outside does not remain peaceful for long. Kane is forced to leave his sanctuary when the land is overrun by a horde of marauding raiders led by a sorcerer who is bent on conquest. On his journey, Kane reluctantly resumes his fighting ways when he rescues Meredith Crowthorn, whose family was slaughtered by the raiders. He pledges to deliver the young woman to safety, and along the way, his resolve is tested as he is drawn deeply into a conflict that calls for the very violence he has forsworn. Battling both his internal demons and the very real ones that stand before him, Kane starts to find his true purpose and realizes that his redemption may be earned through the very means he had hoped to avoid—by taking up arms once again.