After the Contamination - an epidemic caused by the super-trendy diet drink SlimPro that turned ordinary citizens into shambling creatures unable to control their violent impulses - the government rounded up the "Connies" to protect the remaining population. But now, two years later, the government's started sending the rehabilitated back home, complete with shock collars that will either stop the Connies from committing violent acts or kill them before they do any further harm.
Since her parents were taken in the roundup, Velvet Ellis has struggled to care for her ten-year-old sister and maintain a sense of normalcy, despite brutal government rations and curfews. She goes to the "Kennels" every day searching for her parents, and when she finds her mother, she's eager to bring her home. Maybe, eventually, they'll be able to get back to the way things were before. But even though it seems that her mother is getting better (something that the government says is impossible), there will be no happy transition. Anti-Connie sentiment is high, and rumor has it that an even worse wave of the Contamination is imminent. And then the government declares that the Connies will be rounded up and neutralized, once and for all.
Sacrificing everything - her boyfriend, her home, and her job - Velvet will do anything to protect her mother. Velvet has to get the collar off her mother before the military comes to take her away. Even if it means risking all of their lives.