The central plot device is the "macroscope", a large crystal that can be used to focus a newly discovered type of particle, the "macron". Macrons are not subject to many of the effects that interfere with light, and as a result the macroscope can focus on any location in space-time with exceptional clarity, producing what is essentially a telescope of infinite resolution in the space-time continuum. The macroscope has been built into a solar-orbiting space station where scientists visit to book time on the device. Using it, they are able to explore space like never before. Among their many discoveries are numerous planets and two intelligent alien races. Using the macroscope, observers were able to look into one race's historical records, finding numerous parallels with human life on Earth. The race is now in societal decline, and the implications are worrying.