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 has 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.