Asher Sutton returns from a deep-space assignment only to find himself the target of an assassination plot orchestrated by his own people. Sutton possesses knowledge of a galactic secret that threatens the xenophobic status quo of Earth, forcing him to flee across time and space. He must evade relentless pursuers while attempting to complete a manuscript that holds the potential to alter the trajectory of human history. The narrative follows his struggle against powerful political factions, utilizing a third-person perspective that emphasizes the vast scale of the galaxy and the fragility of human destiny.

Readers frequently highlight the philosophical depth Simak brings to the classic space opera format. Discussion often centers on the tension between the protagonist's personal survival and the broader implications of his discovery for the human race. Critics note that the pacing balances intense chase sequences with slower, reflective passages regarding the evolution of civilization. The portrayal of robots as complex, nearly human entities remains a frequently cited element that distinguishes this work from its contemporaries. Many readers appreciate the atmospheric scope of the narrative, which effectively conveys the isolation of a man caught between competing galactic interests.