A young girl, Siren, dreams about water a lot. Siren meets a new boy, Adam, in school and saves him from bullies. She also starts to like him instantly. While in school, Siren discovers that she can move water with her mind. She is freaked out by it and runs home. Her friend, Crystal, comes over and Siren tries to recreate the water bending, but fails, they then decide to go to the beach. Crystal gives Siren an early birthday present, a special necklace. Crystal notices the necklace glowing near Adam and warns Siren to stay away from him. The next day, Crystal, her mother Quinn, and Siren's adoptive mother, Tiffany, sit Siren down to have a serious discussion about something. They reveal to her that she's a half-mermaid, and with her twelfth birthday she would have to go to the sea for three years. Siren doesn't believe them at first, but when she does, she even shows them her water moving powers. THe others then speculate that she might have other powers, which might attract hunters. As it turns out when a mermaid is coming into their power for the first time their blood is special and can heal people, but the power fades after some time. Siren doesn't know how to process all of it and runs to her room to be alone. While taking a bath, her legs starts to transform into a tail, and she climbs out of the tub and passes out. Tiffany brings her to a hospital. Crystal and Quinn are there when Siren wakes up, and they explain more about being mermaid. They also reveal that Siren's birth mother, Emerald is still alive and lives in the ocean, where she is the leader of mermaids. Siren leaves the hospital on her own, and goes to Adam's place. Siren and Adam go for a walk, and Siren reveals that she's mermaid to him. Adam showed Siren some of his dad's things hidden in a container, one of which was a book about mermaids and other sea creatures. When Siren returns home, Tiffany has been up waiting for her, worried. She then gives Siren the airator, for when her gills start to show, the airator would help them breath. The next school day, Siren opts to leave the airator behind, and cover her neck with a scarf instead. In school Adam, reveals that his family are the mermaid hunters, and that siren's blood would help him heal, but Adam doesn't want to use her like that. Siren promises to help Adam on her own terms. Siren starts feeling dizzy, and collapses, Crystal discovers that she doesn't have the airator, and calls pulls a fire alarm to distract other people. The school's principle arrives, who turn out to be a mermaid as well. She gives Siren her airator, and tells Crystal to take her to river room. Adam return to home, and discovers that his dad has left with all the hunting gear, he then goes to the hidden container, which has been emptied as well. The river room is a meeting place for mermaids, who welcome Siren to their ranks. Adam finds the control center for the hunters, and unwillingly reveals that Siren is the mermaid they are looking for. At night the hunters raid Siren's home and capture two mermaids guarding her, and also Tiffany. Adam also came, but he helped siren to escape. Siren goes to the safehouse to prepare for her change. The other mermaids go to the hunters and exchange Principal Strauss for Tiffany, explaining that Tiffany would be the only one who could convince Siren to give her blood willingly. Tiffany runs home, and waits for a while to go to the safehouse, but she was still followed. Fortunately Siren had changed already and was taken to the beach. The hunters tracked them there and tried to capture Siren but were too late. Adam also arrived there and tied to convince his father to drop his hunt and release the mermaids who were on the beach. The father agreed to leave, but one of his men wouldn't listen and wanted to hurt Tiffany, Adam pushed her down, but got hurt by doing it due to his brittle bone disease. Tiffany then called for Siren who came back with her birth mother, and they healed Adam with their magic. It turned out that Siren wasn't half-mermaid but a pure-blood, and could come and go from the sea as she pleased. The over eager hunter still wouldn't give up and wanted Crystal for his research, Siren used her water moving powers on him and killed him. Siren then returned to the ocean with Emerald for couple of months.