Sea of Darkness by Isadora Brown & Rebecca Hamilton

The Society’s sole purpose is to protect the general population from vicious Sea Shadows, and Kelia’s their top Slayer. But when her father is murdered and her handler insists it’s suicide, she starts to question whether The Society really has her best interests at heart.

Now, to solve her father’s death, Kelia must work with an unexpected ally: Drew Knight, an infamous Sea Shadow and the most beautiful creature Kelia has ever set eyes upon. A Sea Shadow who, without intending to, just may show her who the real enemy is…