Advertising consultant Cayce Pollard, who reacts to logos and advertising as if to an allergen, arrives in London in August 2002. She is working on a contract with the marketing firm Blue Ant to judge the effectiveness of a proposed corporate logo for a shoe company. During the presentation, graphic designer Dorotea Benedetti becomes hostile towards Cayce as she rejects the first proposal. After dinner with some Blue Ant employees, the company founder Hubertus Bigend offers Cayce a new contract: to uncover who is responsible for distributing a series of anonymous, artistic film clips via the internet. Cayce had been following the film clips and participating in an online discussion forum theorizing on the clips' meaning, setting, and other aspects. Wary of corrupting the artistic process and mystery of the clips, she reluctantly accepts. Cayce is not entirely comfortable with Ivy's chat group called "Fetish:Footage:Forum" (or F:F:F), as shown by the following excerpt:
There are perhaps twenty regular posters on F:F:F, and some much larger and uncounted number of lurkers. And right now there are three people in Chat, but there's no way of knowing exactly who until you are in there, and the chat room she finds not so comforting. It's strange even with friends, like sitting in a pitch-dark cellar conversing with people at a distance of about fifteen feet.
A friend from the discussion group, who uses the handle Parkaboy, privately emails her saying a friend of a friend has discovered an encrypted watermark on one clip. They concoct a fake persona, a young woman named Keiko, to seduce the Japanese man who knows the watermark code. Cayce, along with an American computer security specialist, Boone Chu, hired to assist her, travels to Tokyo to meet the man and retrieve the watermark code. Two men attempt to steal the code but Cayce escapes and travels back to London. Boone travels to Columbus, Ohio to investigate the company that he believes created the watermark. Meanwhile, Blue Ant hires Dorotea who reveals that she was previously employed by a Russian lawyer whose clients have been investigating Cayce. The clients wanted Cayce to refuse the job of tracking the film clips and it was Dorotea's responsibility to ensure this.
Through a completely random encounter Cayce meets Voytek Biroshak and Ngemi, the former an artist using old ZX81 microcomputers as a sculpture medium, the latter a collector of rare technology (he mentions purchasing Stephen King's word processor, for example). Another collector, and sometime 'friend' of Ngemi's, Hobbs Baranov, is a retired cryptographer and mathematician with connections in the American National Security Agency. Cayce strikes a deal with him: she buys a Curta calculator for him and he finds the email address to which the watermark code was sent. Using this email address Cayce makes contact with Stella Volkova whose sister Nora is the maker of the film clips.
Cayce flies to Moscow to meet Stella in person and watch Nora work. Nora is brain damaged from an assassination attempt and can only express herself through film. At her hotel, Cayce is intercepted and drugged by Dorotea and wakes up in a mysterious prison facility. Cayce escapes; exhausted, disoriented and lost, she nearly collapses as Parkaboy, who upon Cayce's request was flown to Moscow, retrieves her and brings her to the prison where the film is processed. There Hubertus, Stella and Nora's uncle Andrei, and the latter's security employees are waiting for her. Over dinner with Cayce, the Russians reveal that they have been spying on her since she posted to a discussion forum speculating that the clips may be controlled by the Russian Mafia. They had let her track the clips to expose any security breaches in their distribution network. The Russians surrender all the information they had collected on her father's disappearance and the book ends with Cayce coming to terms with his absence while in Paris with Parkaboy, whose real name is Peter Gilbert.https://en.wikipedia.org/wiki/Pattern_Recognition_(novel)