Continuing story of Riley who is half siren and half human. Her mates, Jax, Morgan, and Blake, are merman. Poseidon's son was supposed to be a myth that was killed at birth. Everyone finds out that he was not killed but taken to Zeus to be raised but things happened to him to make him bitter against his father. He has been in the background trying to kidnap Riley so that he can take over by killing his father and releasing the sirens that are in prison. He wants to change the world. Things do not go as planned for Dylan, Poseidon's son, and everyone goes thru a lot of suffering and anguish before they can figure out how to stop Dylan. This was a very exciting series to read and look forward to books that have Riley's childhood friend and her story.