Before the Internet became widely known as a global tool for terrorists, one perceptive U.S. citizen recognized its ominous potential. Armed with clear evidence of computer espionage, he began a highly personal quest to expose a hidden network of spies that threatened national security. But would the authorities back him up? Cliff Stoll's dramatic firsthand account is "a computer-age detective story, instantly fascinating [and] astonishingly gripping" (Smithsonian). Cliff Stoll was an astronomer turned systems manager at Lawrence Berkeley Lab when a 75-cent accounting error alerted him to the presence of an unauthorized user on his system. The hacker's code name was "Hunter" -- a mysterious invader who managed to break into U.S. computer systems and steal sensitive military and security information. Stoll began a one-man hunt of his own: spying on the spy. It was a dangerous game of deception, broken codes, satellites, and missile bases -- a one-man sting operation that finally gained the attention of the CIA...and ultimately trapped an international spy ring fueled by cash, cocaine, and the KGB.

本書是電腦網路界及文學小說界的傳奇，本書寫成於 1980 年代，被譽為最真實的駭客小說。

作者曾經與德國駭客集團鬥智，本書是他以真實經驗所寫成，當時他意發現係統顯示帳款有誤，由他就由這一筆75美分的錯帳開始追查，因而一路追蹤到一項國際性的電腦間諜活動；最後他不僅保護瞭所負責管理的電腦係統，也查齣瞭入侵係統的來源、力擒駭客。這個案件當時登上 New York Times 頭版，轟動全國。

這是第一本由當事人親自執筆撰寫的紀錄，完全的第一手資料，不僅十分具有說服力、讓世人對電腦犯罪案件有瞭最深入現場的瞭解，也引發世人思考電腦世界安全與犯罪的問題和討論。