He emptied the Tideguard for his mistress, and the court fell Episode 3
Episode 3 · Maren Ashforth, Nereus Thorne, Seraphine Voss
Episode 3 recap
Willa points out Maren Ashforth's heavy pregnancy and insists on swimming through the Darkcurrent Trench to find King Nereus and the Tideguard. Outside, invaders pick up the scent of merfolk near the hidden entrance and start smashing it with heavy weapons. Willa comes back thirty minutes later, covered in mud and cut by reefs. She breaks down and tells the waiting survivors that Nereus and his guards refused to help them.