You may think you know how the fairytale goes: a mermaid comes to shore and weds the prince. But what the fables forget is that mermaids have teeth. And now, her daughters have devoured the kingdom and burned it to ashes.

On the run, the mermaid is joined by a mysterious plague doctor with a darkness of their own. Deep in the eerie, snow-crusted forest, the pair stumble upon a village of ageless children who thirst for blood, and the three "saints" who control them.

The mermaid and her doctor must embrace the cruelest parts of their true nature if they hope to survive.