Hells Mouth Child-Eating Demon

My mother, her sisters and offspring are known as Nereids, or sea nymphs. Most of them live in the ocean, but some, like my mother and a few others, choose to live in the forest. My name is Eunice. Every fifty years my Nereid family has to sacrifice a nineteen - year old princess to Lamia, the child-eating demon. Unfortunately for me, the fifty-year pact is this year, and I am the only princess who is going to be the required age soon.
Will handsome-brave Khasius from Helios help me escape my fate? Or will Lamia claim him as well.