A teenage prodigy in the near future has an unusual condition: her immune system is present but nonfunctional — every cell has forgotten what to do. She partners with a team of scientists to develop a nanobot called Explorer that can enter the body and retrain the immune cells to fight infections again. You pilot the Explorer by remote, learning from advisors how different cells and body environments function, and training immune cells level by level against a succession of different infections. An educational action game about the immune system.