Amelia Child has devoted her life to researching Gerald Shapiro, the Catfish Killer, a man who pretended to be other people online to gain women's trust before meeting and killing them. Her book on the Catfish Killer, Into the Glass, earned wild success and a legion of true crime fans. Years later, Amelia is pulled back into the case when a girl from her daughter's high school disappears, and all signs point to a copycat killer mimicking the Catfish Killer's every move.

As Amelia meets with the detective that helped her study Gerald Shapiro years ago and they become suspicious of Shapiro's son, Amelia's daughter Gabby receives a letter from the kidnapper threatening that she might be next. Desperate to find the culprit before her classmate is killed or she becomes the latest victim, Gabby conducts her own search for the missing girl.

With Amelia's own family at risk and the entire true crime world obsessing and investigating online, the stakes have never been higher. Everyone wants to find the killer-but when his modus operandi is to pretend to be someone else, he's not going to be easy to catch.