Arthur Curry, a lighthouse watchman, is called upon by people of the lost underwater city Atlantis who need his help. Arthur realizes he's half-Atlantean, allowing him to breathe underwater, swim with ease, control water, and communicate with sea life. With some help from underwater allies, Arthur must stop both his half-brother Orm, the current ruler of Atlantis, from turning all of the surface world into his own underwater kingdom, as well as a technologically advanced cutthroat pirate mercenary who seeks vengeance.
