A group of university friends book a seaside vacation at an Airbnb run by an artist, Tyler. He appears mysterious and guarded since the loss of his wife and daughter. Tyler spends time wondering the beach at night, and comes across a woman who appears to have been washed up on the seashore. He decides to rescue her. Meanwhile, the friends enjoy some drinks at the Airbnb – until one of them vanishes. Then another. And another. A ghostly mermaid with barnacle-covered skin and torn fins begins stalking them from the ocean, luring them with singing before killing them in brutal, symbolic ways-slashing, drowning, dismemberment.