Gemma loves swimming. Her dream is to make it to the olympics so she is practicing hard. Not a session with her coach missed. Along the way, the fell in love with Alex, the boy nextdoor (literally) who is also her sister's bestfriend. Gemma, her sister Harper lives with their father Brian. Their mother is mentally unfit to be living with them after a car accident.
Gemma's water and swimming addiction has attracted a group of girls' interest. What she didn't know is these girls are not only amazingly beautiful but they are also cursed. One night, when Gemma was swimming in the ocean, the girls lured her to join their "party". Little did she know it was a trap to make her a siren like the other girls.
With the recent disappearance of boys and girls in the neighbourhood, her father has set a curfew for her to be back at 11:00pm. The party she attended caused chaos when she didn't return until she was found on the beach the next morning. She noticed changes in herself as well but she could not be certain until she had a talk with the other sirens. That also gave her answers to the mystery behind the people disappearances in the neighbourhood.
She has to make a decision now; follow the sirens to stay alive or stay back with her loved ones and die....