This document analyzes how fans of the "Serial" podcast collectively developed theories and interpretations of the case on subreddit forums like r/serialpodcast. It discusses how fans worked together to fill in narrative gaps, sometimes creating their own speculative versions of events ("fanon") in a way similar to fan fiction writers. However, these conspiracy theories sometimes led to false accusations or doxxing of innocent people. The document examines this community through the lenses of participatory culture, transformative works, and collective meaning-making online.