Originally published in 1967, Logan’s Run is a science fiction novel. In the world of 2116, a person’s maximum age is strictly legislated: twenty one years, to the day. When people reach this Lastday they report to a Sleepshop in which they are willingly executed via a pleasure-inducing toxic gas. A person's age is revealed by their palm flower crystal embedded in the palm of their right hand that changes color every seven years, yellow (age 0-6), then blue (age 7-13), then red (age 14-20), then blinks red and black on Lastday, and finally turns black at 21. The story follows the actions of Logan, a Sandman charged with enforcing the rule, as he tracks down and kills citizens who “run” from society's lethal demand, only to end up “running” himself.