Like a Curse by Elle McNicoll

Stuck in Loch Ness while Edinburgh falls under the control of a terrifyingly powerful Siren, Ramya Knox is frustrated. She's supposed to be learning magic from her Aunt Opal, but that isn't going as smoothly as she'd hoped. As she pushes to rescue her Hidden Folk friends in the city, long-buried secrets come to light and legends come to life.

Ramya knows she's different; she knows she's a witch. But now she must learn the true meaning of her powers... before all she loves is lost.

(Follw up to Like a Charm )