Alastair Reynolds tells a tale that is much larger in scope than it first appears to be. It all starts innocently enough with the crew of the Rockhopper doing what they do best, mining comets in our solar system, also known as "pushing ice." Then something unexplainable happens. One of Saturn's moons, Janus, breaks out of orbit and assumes a trajectory toward Spica, a star 240 light years away. Not only that, it is accelerating as it heads out of the solar system. This brings an abrupt end to the existing mission for the Rockhopper crew as they are the only ship capable of intercepting Janus for a few days before it leaves our solar system for good. They are a crew of miners, not explorers, but they are the only ones who can study Janus up close before it is gone so all of mankind turns its attention onto them.