In the year 2116, the world is run by young people under the age of 21 with a hedonistic approach to life in their utopian society. Following the Little War in the 20th century, the human population became unsustainable in the subsequent century, forcing the use of voluntary euthanasia at the cutoff age.
Upon reaching 21 years of age—indicated by a palm flower implant— an individual undergoes a painless execution through a toxic gas at a Sleepshop. The flower implants change color with an interval of seven years since birth starting with yellow, then blue in the preteens, and red until the Lastday when it turns black. This world is controlled by a computer system located under Crazy Horse Mountain and also connected through a subway system.
Logan is an operative tasked with terminating Runners—people who fail to report at the Sleepshops—who has to run himself now that he has turned 21. He infiltrates the subway system that facilitates the journey to the Sanctuary where runners seek asylum away from the ageist society. In his path, he meets Jessica with whom they work their way to the sanctuary in the next 24 hours while escaping their fate. They are joined by Logan’s colleague Francis who attempts to kill him due to his mistrust but later reveals his true identity. He is the legendary Ballard, the man who works to help escapees reach the Sanctuary and is actually 42 years old despite his appearance.
Through their adventure, Logan has a shift of mindset becoming what he once worked hard to eliminate. With the global system starting to show signs of breaking down, Logan and Jessica learn more about their world and the asylum. The Sanctuary is located in outer space in a colony called Argo. They launch from the old space field center to join other Runners while Ballard continues his crusade of saving others.
