Sixteen-year-old Caterina eats seaweed instead of buying school lunch. She rallies shamelessly for the ocean, even using school art and science projects as leverage. At Church, she plays her mandolin and sings every Sunday in the choir loft. And she doesn't know why everyone thinks she's so strange ...But if all of that is not enough to make a girl stick out at monotonous--and landlocked --Hillnook High School, Caterina has a huge secret; one that justifies her weirdness: she is really a mermaid. Like all mermaids do, Caterina attracts the attention of a boy via her singing, though not on purpose: Luc Malone is in the choir loft one day at church, and gets an up-close earshot of mermaid music...But when heartbreak inevitably strikes, Caterina, with the help of her mermaid cousins, must embark on an Atlantic journey to ask the wise creatures of the sea...Was it just a siren song, or is it true love?