1986 gave the world one of the strangest detective stories in computing. Clifford Stoll, an astronomer working at Lawrence Berkeley Laboratory, was checking a routine billing report when he noticed something tiny. A missing 75 cents in computer time fees. It looked like a harmless accounting slip, but something about it bothered him enough to double check. That curiosity pulled him into a ten month investigation that took over his life. While digging through login records, network trails, and late night anomalies, Stoll found signs that someone was slipping into the lab’s computers. The deeper he looked, the more he realized the intruder was not a careless student or a glitch. It was a German hacker quietly breaking into US research networks, including military systems, and selling the stolen data to the KGB. Stoll built homemade traps, traced connections through phone lines, and gathered logs long before cybersecurity became a field. His work finally exposed the hacker ring and helped authorities shut it down. All of it started because he refused to ignore 75 cents.