Not long after the invasion and occupation of Earth by a race of powerful robots wanting human knowledge and ingenuity, humans are confined to their homes. Leaving without permission would be to risk their lives. Monitored by the electronic implants in their necks, the robot sentries are able to track the movement of humans in order to control them. If any person attempts to exit their home, they are given warnings by the robot sentries to return their home. If he or she does not comply within ten seconds, they are killed.