The series Westworld corresponds to what Matt Hills qualifies as a puzzle masterpiece. Complex, its science-fiction story leaves many riddles hanging which a community of spectators seek to elucidate. Their hypotheses, which rely on meticulous viewing, are the object of many debates on social media. Bearing the name of “fan theory”, these speculations focus on details spotted in an episode susceptible of giving away a hidden meaning. By taking an interpretation of Wesworld proposed by the vlogger “The Film Theorist” as an example, this article is about different aspects of a phenomenon anchored in web culture. His analysis exposes both the comprehension and the pleasure which fans can get from the contemporary narrative canons.