Secret of the Sirens by Julia Golding

When eleven-year-old Connie is sent to live with her eccentric aunt by the sea, she's not expecting anything great-not to make friends with Col, the coolest guy in town, and certainly not to discover that mythical creatures still exist, that an ancient society has protected them for centuries, and that a dark and treacherous force is lurking in their midst.

https://rapidgator.net/file/d434c2796cf768dc49d895ebe5e0ae8c/

http://nitroflare.com/view/227463A8D61B98D/