Wayfair, an American furniture and home goods retailer, garnered sudden attention across social media in 2020, particularly Twitter and Reddit, due to a conspiracy theory linking the company to child trafficking. The short-lived, well-delineated nature of this theory, coupled with its simultaneous emergence across multiple platforms, makes it a distinct case for studying the dynamics of online conspiracy development and spread. Using intermedia agenda-setting theory and computational approaches, we analyzed 1.2 million posts to explore cross-platform interactions. We examined how platform affordances shaped discourse and enabled the conspiracy\u2019s dissemination. Reddit\u2019s anonymity and detailed discussions sustained narratives, while Twitter amplified emotional content and broadened the audience. Hourly time-series analysis reveals a bidirectional influence: Reddit set thematic agendas that Twitter amplified, while Twitter\u2019s emotional content shaped Reddit\u2019s discussions. These findings shed light on the digital development of child abuse conspiracy theories while advancing the understudied aspects of intermedia agenda-setting literature.<\/p>\n\n\n\n