Living on a magical island should be perfect ? but Emily and her family and friends jump at the chance to go home to Brightport and carry out Neptune?s orders to bring humans and merfolk together.

There, thrown out of mermaid school and scorned by her old enemy Mandy Rushton, she goes in search of the lost sirens, banished by Neptune to a secret underground cavern. It?s only when she uncovers their story that she can begin to reconcile her two worlds. But can she do it in time to save herself and her family from the wrath of Neptune?