In a future world where teenagers are taken, imprisoned, and forced to fight for their survival, well-behaved Cassie will do whatever it takes to save her rebellious twin sister from Death Row.

The Great War is over. The Robots have won. The humans who survived have two choices--they can submit and serve the vicious rulers they created or be banished to the Reserve, a desolate, unforgiving landscape where it's a crime to be human. And the robots aren't content--following the orders of their soulless leader, they're planning to conquer humanity's last refuge. With nothing left to lose, Six, a feisty, determined young woman whose family was...