[Machine Translation] The runaway humanoid security unit, "Our Machine," is caught up in an alien relic contamination incident on a colony planet, but with the help of ART, the Perihelion exploration ship, it is able to escape its predicament. However, the ruthless corporation that is after the planet has not given up. And when a mysterious obstacle strikes their ship... The long-awaited fourth installment in the popular series that has won four Hugo Awards, two Nebula Awards, five Locus Awards, and the Japan Translation Award! Winner of the Locus Award.