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 users on his system. The hacker's code name was "Hunter"-- a mystery invader hiding inside a twisting electronic labyrinth, breaking into U.S. computer systems and stealing sensitive military and security information. Stoll began a one-man hunt of his own, spying on the spy-- and plunging into...