When his title is threatened, Arthur Curry returns to Atlantis to defend his throne as king. Opposing him is his brother, Orm Marius, infamously known as Ocean Master. Arthur doesn't take this threat lightly and advises Orm and his men to back down, to no avail. Having consulted with his mentor, Nuidius Volko, and his wife, Mera, Arthur has no other option but to take on his brother.