The Swarm is unrecognizable, untraceable, and unpredictable--random attacks on the streets of Chicago by a mob of crazed teens that leave death in their wake. It's been two years since the last attack, but Lia Finch has found clues that reveal the Swarm is ready to claim a new victim. She's the only one still pursuing her father's killers, two years after attorney Steven Finch's murder by the Swarm. Devastated and desperate for answers, Lia will do anything to uncover the reasons behind his death and to stop someone else from being struck down. But due to debilitating asthma and PTSD that leaves her with a tenuous hold on reality, Lia is the last person who should mount a crusade on her own. After a close encounter with the Swarm puts Lia on their radar, she teams up with a teen hacker, a reporter, and a mysterious stranger who knows firsthand how the mob works. Together, they work to uncover the master puppeteer behind the group. But if Lia and her network don't stop the person pulling the strings--and fast--Lia may end up the next target.