In the 23rd century, humans forsake the ravaged outer environment by living in a vast, bubbled metropolis. There, computerized servo-mechanisms provide all needs and everyone can pursue endless hedonism. Endless, that is, until Lastday. That's when anyone who's 30 must submit to Carrousel, a soaring, spinning trip to eternity and supposed rebirth. Logan 5, a Sandman authorized to terminate Runners fleeing Carrousel, decides to become a Runner himself once he finds out the horrible truth about Lastday.