Arya never really thought of mermaids being existed in real life. All her life was filled with depts and pain at every turn, and now suddenly she came to a situation where she might be a mermaid in her past life. She remembered falling in love with a prince and getting betrayed by him, but there's much more. A stupid professor who funded her own research about mermaids, an old castle whose walls hold the memories of her past time, a lost heart- a red ruby and her cold-hearted prince.