In corporation-run Satellite City, orphans are used for dangerous product testing. 14-year-old Cosmo manages to escape from the orphanage, nearly getting killed in the process, and finds that he has the ability to see invisible blue creatures that are attracted to accidents and violence, and seem to suck the life out of injured people. He teams up with Stefan, Mona, and Ditto, who have the same ability, and spend their nights seeking out and shooting the Parasites.
But nothing is as it appears. Stefan has a relationship with the corporation that runs the city and is chasing them, Ditto may not be leveling with them about his own motives, Mona is close to a local street gang, and the Parasites, and their deaths, may not be what they appear.