In the Heart of Danger - Watermark chronicles; book one

Rosalina Jessica is new at her school. She meets new people. She's everything a girl would want to be, besides the fact that she is a blood-thirsty mermaid. She meets new people who are like her. During this she meets her worst enemy and falls in love. Now, the threat agianst her kingdom is small, but it could get bigger. She must go to battle and save her kingdom. But will she be able to stay at her own town if she is victoious?