In 1986, Cliff Stoll\u2019s boss at Lawrence Berkeley National Labs tasked him with getting to the bottom of a 75-cent accounting discrepancy in the lab\u2019s computer network, which was rented out to remote users by the minute. Stoll, 36, investigated the source of that minuscule anomaly, pulling on it like a loose thread until it led to a shocking culprit: a hacker in the system.