Television storytelling is one of the most vibrant, dominant fictional modes of the twentieth and twenty-first centuries, and yet its foundational structure, the episode, has been undertheorized. All television stories deploy the episode in some way, and its formal and fictional contours are both inescapable and distinct from existing narrative theories of other serial forms. This essay is an attempt to provide a narrative theory of the television episode as a form, one that accounts for plot-based episodic storytelling as well as episodes built around a thematic structure, and it outlines a common framework for all fictional episodic expression on television. To do this, the essay considers several key texts, including Mad Men, House, and Friends, and explores the episode in contrast to the theories of narrative parts and wholes provided by works like Barthes's "Structural Analysis." The essay also gestures towards a longer history of episodic storytelling in television through shows like I Love Lucy and Twilight Zone, and also notes more recent developments in streaming television storytelling, where the episode's diminishing formal weight is growing more palpable.