It got me at "mermaid" (mention of other mythological creatures will do the trick as well). I watched the movie first, and then intrigued by it -- searched for the title and found that it was based upon a book. I must say that I am very pleased that the book and movie are almost completely identical to each other in rendition, from scenes to dialogue. I would say that this book is about longing and long-suppressed ache. Whether one runs from, or buries these 'desires', there will come a time of over-satiation, which results in eruptive and/or disruptive behavior -- or as a character in the book says, "We will be both damned and saved!" You can watch the movie for free on Amazon Prime.