The protagonist is an unnamed narrator and fugitive. After escaping his pursuers and arriving on a remote island, thinking that he is completely alone, the narrator reflects on his situation:

I was dead to the world, a ghost of a man. Someone that used to exist.

The author, Casares, is raising an interesting issue: to what extent does our existence rely or depend on others to be real or meaningful? Does a solitary life away from human society have purpose or meaning?

The fugitive's alienation doesn't last long as he encounters a group of well-heeled revelers that don't acknowledge him or even appear to see him. The fugitive falls in love with one of these attractive phantom figures and states:

I'm not dead anymore, I'm in love.

Love reanimates the fugitive and gives him purpose. He doesn't really know the woman, and he can't communicate with her. He only sees her.

Eventually he discovers that a previous inhabitant of the island, one Dr. Morel, has created a kind of virtual reality machine that can grant a limited immortality to the people whose souls are uploaded into his machine. The catch is that they only get to repeat the events of one week for all eternity. After discovering what he has been witnessing, the fugitive at first despairs.

To be on an island inhabited by ghosts was the most unbearable of nightmares. To be in love with one of those images was worse than being in love with a ghost.

Eventually, he decides to try and join his phantom love in this strange partial immortality, so he can be with her on an eternal playback loop.