After modern science turns every human into a genetic time bomb with men dying at age twenty-five and women dying at age twenty, teenaged Rhine finds hope for a brighter future from a surprising source.

In a future where genetic engineering has cured humanity of all diseases and defects but has also produced a virus that kills all females by age twenty and all males by the age twenty-five, teenaged Rhine escapes her forced marriage and journeys back to New York to find her twin brother.