The Deep Dark — Molly Knox Ostertag

From Molly Knox Ostertag, writer-illustrator of the New York Times and ABA Indie bestselling The Witch Boy trilogy and The Girl from the Sea, comes a darkly beautiful story of identity, family, love, loss, and magic.
Everyone has secrets. Mags's has teeth.

Magdalena Herrera is about to graduate high school, but she already feels like an adult with serious responsibilities: caring for her ailing grandmother; working a part-time job; clandestine makeouts with a girl who has a boyfriend. And then there's her secret, which pulls her into the basement each night, drains her of energy, and leaves her bleeding. A secret that could hurt and even kill if it ever got out -- like it did once before.

So Mags keeps her head down, isolated in her small desert community. That is, until her childhood friend Nessa comes back to town, bringing vivid memories of the past, an intoxicating glimpse of the future, and a secret of her own. Mags won't get attached, of course. She's always been strong enough to survive without anyone's help.

But when the darkness starts to close in on them both, Mags will have to drag her secret into the daylight, and choose between risking everything... or having nothing left to lose.