From the New York Times bestselling author of All the Missing Girls and The Perfect Stranger comes a captivating thriller about two teens who connect when each discovers a mysterious radio frequency, which suggests their family tragedies are mysteriously connected.

After surviving an infamous family tragedy, sixteen-year-old Kennedy Jones has made it her mission to keep her brother's search through the cosmos alive. But then something disturbs the frequency on his radio telescope--a pattern registering where no signal should transmit.

In a neighboring county, seventeen-year-old Nolan Chandler is determined to find out what really happened to his brother, who disappeared the day after Nolan had an eerie premonition. There hasn't been a single lead for two years, until Nolan picks up an odd signal--a pattern coming from his brother's bedroom.

Drawn together by these strange signals--and their family tragedies--Kennedy and Nolan search for the origin of the mysterious frequency. But the more they uncover, the more they believe that everything's connected--even their pasts--as it appears the signal is meant for them alone, sharing a message that only they can understand. Is something coming for them? Or is the frequency warning them about something that's already here?