The Cuckoo's Egg: Tracking a Spy Through the Maze of Computer Espionage is based on a true story where Stoll discovered a malicious hacker who used the network from Lawrence Berkeley National Laboratory without authorization.

Stoll worked as an astronom in the Lawrence Berkeley National Laboratory but was shifted to the computer department because of lack of work. There it happended that he discovered an accounting error of 0.75$ for unknown network usage. While researching the reasons for this he came to the conclusion that someone used the resources without authorization and is later able to log all sessions of the hacker with help of a printer. While contacting the FBI, CIA, NSA and Air Force OSI it seems that they are not very interested or don't feel responsible for this and therefore aren't of any help.

Throughout the following months Stoll is able to gather always more information about the hacker. With help of the gathered logs he is able to follow all steps done by the hacker and discover important things about the reasons behind the intrusion. To force a longer establishement, he later creates big files which are downloaded by the hacker which led to a longer period of possible monitoring. This was necessary due to the old technique used in Germany for communication. While in most countries of the USA the communications were already digital, Germany used some analog technique. Therefore it was on the German's side not possible to set up a interception circuit within a few seconds.