An American Special Forces soldier, serving in Kenya, suffers memory loss after being knocked unconscious during a battle with highly electrified bipedal robotic machines. He later wakes up in a jail cell wearing tattered fatigues and unaware of anything but memories of intense pain. He meets Nadia, a French foreign aid military doctor in the adjacent cell who tells him he “sounds American” and they were taken prisoner by a gang of xenophobic thugs. She calls him “Bo” after seeing the letters on his torn name tag. Nadia explains to Bo that the world had been invaded by alien machines which wiped out all the major cities and now systematically hunt down survivors.