Hewlett was hit by an epidemic in 2156 which they named the X virus. When the epidemic slightly declined the government divided the people into two groups, the Suffocators who are carries of the disease and the Breathers who are immune. Rosa is being held in one of the "Houses" created for all those presumed to be Suffocators. They get tested at age nineteen when the virus is first be detected. Rosa and her best friend Haley will learn just how divided their world is and what secrets it has to hide.