This chapter takes an ecogothic approach to Leonora Sansay’s 1808 work, The Secret History; or The Horrors of St. Domingo, a Philadelphia woman’s epistolary account of the last years of the 1791–1804 Haitian Revolution. An emerging mode of ecocriticism that examines the fear and horror evoked by representations of nature, the ecogothic approach allows for an investigation into the nonhuman forms of monstrosity that haunt Sansay’s text. While most critical accounts of The Secret History examine its representation of the complex social and political aspects of the slave revolution at Saint Domingue, this study centers instead on its environmental history through an investigation of the novel’s characterization of the mountains of Saint Domingue as both space and agent of horror. Sansay’s text positions this geographic entity as a villainous gothic presence while attempting to deny the existence of the plantation economies that created it. The plantation system’s agricultural practices created a monoculture that brutally exploited both human and nonhuman beings—slaves as well as trees, soil, and plants. Throughout the novel, deforestation’s effects act as interactive agents in Sansay’s plot, simultaneously disguising and revealing the colonization that caused the environmental degradation.