High above planet Florinia, the Squires of Sark live in unimaginable wealth and comfort. Down in the eternal spring of the planet, however, the native Florinians labor ceaselessly to produce the precious kyrt that brings prosperity to their Sarkite masters.

Rebellion is unthinkable and impossible. Not only do the Florinians no longer have a concept of freedom, any disruption of the vital kyrt trade would cause other planets to rise in protest, resulting in a galactic war. So the Trantorian Empire, whose grand plan is to unite all humanity in peace, prosperity, and freedom, has allowed the oppression to continue.

Living among the workers of Florinia, Rik is a man without a memory or a past. He has been abducted and brainwashed. Barely able to speak or care for himself when he was found, Rik is widely regarded as a simpleton by the worker community where he lives. As his memories begin to return, however, Rik finds himself driven by a cryptic message he is determined to deliver: Everyone on Florinia is doomed…the Currents of Space are bringing destruction. But if the planet is evacuated, the power of Sark will end-so there are those who would kill the messenger. The fate of the Galaxy hangs in the balance.

艾西莫夫(Isaac Asimov,192O-1992) 是美籍犹太人，为本世纪最顶尖的科幻小说家之一，曾获代表科幻界最高荣誉的雨果奖和星云终身成就「大师奖」。以他的名字为号召的「艾西莫夫科幻杂志」，是美国当今数一数二的科幻文学重镇。

「基地」、「机器人」 等系列是艾西莫夫最脍炙人口的代表作。这些看似各自独立的故事，相互贯串起来，竟是一部俯仰两万年的长篇史诗！艾西莫夫特意将科幻场景巨幅拉大，在全银河的背景下架构他独有的科幻世界、藉由银河帝国的兴亡史来讨论人性与政冶、经济、军事等文明要素产生的互动影响。这种宏观视野使他的作品处处闪动著关怀人类未来的笔触，超越一般科幻作品的局限。

艾西莫夫不仅是哥伦比亚大学的化学博士，更是世闻名的全能作家，一生著述多达百七十余本，内容广及科学类的数理化、天文、生物、医学，还旁涉人文类的文学、宗教、史地等。如此渊博的学识使他的笔下世界具备了奇幻的想像与高度的预言性。在他刚开始写机器人小说时，机器人学未发展出来；等到这门科技发展得相当有成果时，几乎每一本有关机器人学发展史的书籍都提到他、他的小说与他发明的「机器人三定律」。这定律几乎成了以后科幻作家创作有关机器人的作品时必须遵循的法则。 艾西莫夫以真确的物质科学及人文现象演绎出他的科幻世界，又杂进侦探与推理的小说技法，使得他的作品情节生动，扣人心弦，让人不忍释卷。