Following the death of her father, seventeen year-old Grace Celadon moves with her twin sister to a lavish island off the coast of Massachusetts. There, the sisters become entwined with an enchantingly reckless group of teens. Like two sides of a single coin, the twins spiral fast and wild into a blur of drugs and alcohol. When strange things begin to happen all around them, Grace starts to wonder whether it is more than just the frightening hallucinations of drug highs that plague them. She begins to question whether it's possible that something sinister has rolled in from the breathtaking cliffs and pastures of the island to find them.