Over the second half of the nineteenth century, the United States established itself as a leading global economy, and in the midst of this combustible ascent print capitalists reorganized their industry along two grooves – book and periodical publishing. This paper examines Louisa May Alcott’s sensation story, “The Mysterious Key, and What It Opened,” and Henry James’s Daisy Miller, two intermediate-length works of prose fiction that, precisely because of their length, fell between those grooves that have come to structure the modern print industry. Longer than the short-form fiction that appeared in nineteenth-century periodicals but shorter than the typical novels published by the book trade, these works inhabited a space of industrial irrationality – a space where publishers made huge profits or went broke, and where literary form became subject to severe distortions and taxonomic confusions. Whether stories of this length were, for all their aberrance, the best, most aesthetically pleasing works of literature or, in fact, the worst, has remained unclear to many participants in American literary culture since the turn of the twentieth century. By studying print capitalism between the book and the periodical, this paper hopes to confront some of the discipline’s basic assumptions about the shape of literary form and its valuation.