Four girls. Four girls skating home, both sides of the road, fearless. Four girls at the mouth of an infinite ocean, sugared and salted with sand and seawater, the tide licking their sunburned feet. This summer, they're going to disappear. For seventeen-year-old Callie and her best friend Talia, every summer in their small North Carolina beach town is as familiar and steady as the tides. Their long-distance friend Cleo arrives from DC, and they spend their days lazing on the sand and their nights working at the local roller-skating rink. But this summer, Cleo has brought along Polly, an enigmatic girl who shakes up the dynamics of the group. And Cleo has a proposition, gleaned from private YouTube video tutorials and hidden message boards: They're going to learn how to make themselves invisible. Callie thinks it's a ridiculous, impossible idea. But the other girls can't help but be intoxicated by the thought of disappearing, even just temporarily-from bad boyfriends, from overbearing families, from the confusing, uncomfortable reality of having a body altogether. When Callie gives in and they finally try it, miraculously it works. Yet as the summer progresses and the girls revel in their reckless new freedom, they realize it's getting harder and harder to come back to themselves. And, for some of them, do they even want to?