Quinn Vasquez has always believed that Cassandra Diaz was just a girl in her head, an impersonation of her deepest, darkest thoughts—but she was wrong. Cassandra is real, and she's only growing stronger. Quinn is convinced that she was involved in the disappearance of one of her closest friends, her leads taking her beyond the Metropolis' bounds, straight into Cassandra's territory. She shares her mission with Julio, a boy with the same determination to stop Cassandra. However, he has a few quirks of his own, mainly concerning his past with an ex-lover. He remains secretive about the topic, and only shares his life in obscure little pieces. His world is a deep, mysterious ocean, and Quinn is no longer sure what she'll find if she dives in. In the quest to stop Cassandra, travel beyond bounds to uncover more secrets the Metropolis keeps hidden.