The setting starts sometime in the 1980s, where we find Atlantean queen Atlanna (Nicole Kidman) coming up to the surface in the state of Maine to get away from an arranged marriage, seeking a bit of sanctuary and time to heal in a lighthouse run by a human named Tom Curry (Temuera Morrison). The two unlikely partners fall in love, eventually leading to a son, Arthur Curry. The kingdom of Atlantis is not pleased with Atlanna’s apparent defection to the land, sending out their soldiers to claim her back, culminating in Tom being left alone to raise the boy himself as a human, except one with the powers of Atlanteans in his DNA, including an ability to talk to and command all forms of marine life.
We fast forward to Arthur’s adulthood, known to the land-dwellers as “The Aquaman” after a series of public acts of heroism, one including taking down pirates that includes future nemesis Black Manta (Yahya Abdul-Mareen II). However, Arthur has to become a savior to his adopted people when the current rule of Atlantis, Arthur’s half-brother Orm (Patrick Wilson), is looking to mount a war with the land walkers who continue to pollute the oceans, seeking the assistance of King Nereus (Dolph Lundgren), one of the leaders of the ‘seven seas’ needed to approve. Nereus’s daughter Mera looks to recruit Arthur’s assistance in staving off the uprising from his brother’s charge. Arthur must go undersea to make his presence felt, but the opposite of a fish out of water in his new environs in the Atlantean realm, especially when the situation boils down to a mano-a-mano battle between Arthur and Orm on his home turf (or non-turf, as it happens to be).