Centuries after nuclear war has destroyed our planet, humanity struggles to rebuild. It's been a month since the dropships landed and the rest of the Colonists joined the hundred on the ground. The teens, once branded juvenile delinquents, are now leaders amongst their people. But suddenly, a new threat looms on the horizon - something neither Colonists or Earthborns have prepared for. In this thrilling fourth installment, Clarke, Bellamy, Wells and Glass are pushed to the limits as they fight to protect their people...and to survive.