Seventeen-year-old Anna Ryan can see emotions as tangible threads. Most threads are pure and bright, but Anna’s are dark, and they can harm anyone they touch.

Secretive and cold, Leir Matoa is the last person Anna wants to be around, no matter how good he looks in board shorts. Unfortunately, he’s the only one who can teach her how to control her threads and weave them into powerful protective shields. He offers to train her in exchange for her help in finding and capturing his fugitive brother. Anna agrees, because shields mean safety, right?

But something terrifying lurks in the spaces between the threads, something unstoppable that uses Anna to break out into the physical world. As Anna and Leir try to contain the creature in the wake of an agonizing betrayal, Leir comes to realize he can’t save the girl who pulls at his heart like no one ever has, while Anna must decide if she should continue to fight her darkness, or place her safety and identity in the hands of a monster who could end her.