In this article we examine young children's outdoor narrative play as animated by the possibilities of running. Guided by posthuman perspectives, the provocations of sociomateriality, and the capacities of mycelial networks, we consider how stories and storying might occur in and as movement. We draw on interdisciplinary understandings of moving lines to map, analyze, and reimagine the compositional dynamics of two assemblages of outdoor narrative play. Following the compositional lines of these assemblages, we reencounter narrative play as embodied and moving occurrences in the indeterminate, overlaying, and un/raveling movements of a relational world. We come to see stories as other than objects of uniquely human composition, but rather as material, authoring subjects entangled in the unfolding of children's literacies and the dynamics of narrative play. We suggest attention to and engagement in such understandings as part of the living lines though which literacy education might newly tell stories about stories.