Atlantis trembles as a ghost‑city, Necrus, rises armed with sun‑drinking tridents. A tide‑born prodigy (Timothée Chalamet) claims a drowned dynasty and offers Arthur a choice: kneel to “unity” or let the oceans turn on the surface.

Mera hears the currents sing in a stolen key; storms repeat a single name. Biolum trenches, coral mechs, and a whale‑back pursuit crash into a molten‑rift siege where loyalty is pressure‑tested. Arthur risks the crown to save the commons, teaching his rival that strength without mercy is only noise. Banter breaks like surf, romance steadies the helm, and a final wave redraws the map.