In the near future, the unmanned Pilgrim 7 space probe returns from Mars to Earth orbit with Soil test potentially containing evidence of extraterrestrial life. The probe is captured and its samples retrieved by the International Space Station and its six-member crew. Astrobiology Hugh Derry, who is paralyzed from the waist down, revives a dormant cell from the sample, which quickly grows into a Multicellular organism that American school children name "Calvin." Hugh realizes that Calvin's cells can change their specialization, acting as muscle, neuron, and photosensory cells all at once.