A boating accident runs a young man and woman ashore in a decrepit Spanish fishing town which they discover is in the grips of an ancient sea god and its monstrous half human offspring.

Ezequiel: No one leave Imboca. People come, but no one leave.
Paul Marsh: What happen with all people in this town?
Ezequiel: They're changing. Changing to go into the sea.
[last lines]
Uxía Cambarro: Pablo, it is your destiny.
Paul Marsh: You stay away! I'll kill you all! I'll burn this fucking town to the ground!
Uxía Cambarro: We had different mothers, but the same father. We are children of Dagon.
Paul Marsh: You're a bunch of freaks. A bunch of fucking freaks!
Uxía Cambarro: Your dreams. Remember your dreams, Pablo. They brought you here.
Paul Marsh: No. They were nightmares. They weren't real.
Uxía Cambarro: Every dream is a wish.
Paul Marsh: [Paul collapses] Somebody help me! What's happening to me?
Uxía Cambarro: You are my brother. You will be my lover - forever.
Paul Marsh: [setting himself on fire] No possibilities.
Uxía Cambarro: Pablo! No! No! No!
[she drags him down into the sea where the flames are extinguished, and they swim away into the depths together]
Intertitle: "We shall dive down through black abysses... and in that lair of the Deep Ones we shall dwell amidst wonder and glory forever." - H.P. Lovecraft
Uxía Cambarro: Before you came, there had been no sacrifices for a year. Dagon needs her.
Paul Marsh: Fuck Dagon!
Uxía Cambarro: Yes, and their child will be immortal!
Paul Marsh: Yeah, but there's a catch. It has to live the rest of its life as some kind of half-ass fish of the sea.
Uxía Cambarro: [agreeing] In joy, with Dagon!
Uxía Cambarro: You cannot care for her. You do not dream of her! You will go soon to a beautiful place. You will forget your world and your friends. There will be no time, no end, no today, no yesterday, no tomorrow - only the forever and forever, and forever without end. It is your fate. It is your destiny.
Uxía Cambarro: Once he was young, and rich, and handsome - for a man. He brought women to Imboca. Outsiders. Your mother.
Uxía Cambarro: I still have human feelings.