Santiago escaped kidnapping, torture, and near death last time she was in the ocean. Now back on the safety of land she resumes life as normal, but finds she is plagued with lingering effects of the Sirens' brutality and thoughts about the world under the surface. When she finds shocking information in her abuela's journals, Santi must make a choice that will decide not only her fate, but also that of millions of others.

Will Santi choose to follow her destiny and return to the ocean to face the demons of her past? And what of her budding feelings for her long-time best friend Rogan? The only thing certain is that Santi's decisions will change the course of her life forever.