This article argues that the cultural semiotic model of the “semiosphere” by Lotman (Lotman, Grishakova and Clark 2009) can be productively employed to interpret the complex layers of social order and liminal sociality in Daniel Defoe’s A Journal of the Plague Year (1722). Defoe’s text, analysed with a cultural semiotic approach, appears as more than a shocking re-narration of a historical event, as it becomes possible to read this proto-novel as a text that showcases and makes experiential the entanglement of social breakdown and social needs. London during the plague is shown as a space that labours to enforce both discursive as well as physical borders, but fails in both instances: The lively media public which Defoe depicts for the mid-17th century is shown as failing to establish boundaries of ‘facts’ and ‘fake news’, while single human beings constantly defy the shutting orders of the authorities, or flee the city illegally. In the semiosphere of a London constituted by a state of exception, Defoe strategically inserts permeable boundaries to show a survival of conviviality in the face of the breakdown of society. The main topoi of Lotman’s cultural semiotic model – explosion and periphery – illustrate both the discursive disorientation during the plague as well as the spatial peripheries of the city as sites of liminal social survival in the face of catastrophe.