The article examines intertextuality as conscious dramaturgical strategy in the composition of Sarah Kane’s 4.48 Psychosis. Inspired by Jörg Helbig’s notion of intertextual marking, the analysis identifies intertextual inscriptions in the play and examines the relationship between manifest text (the text the author produces) and referent text (the text the author borrows from). Kane’s engagement with depression, psychosis, and suicide is mediated through ideas and structures that she adapts from a range of sources. Each of these frames and re-frames the experience of individual suffering explored in the text, and together, they chart the I’s journey from depression to psychosis to suicide. Moreover, the play contains a critique of diagnostic psychiatry and plays out medical discourses against poetic (counter) discourses that reveal mental illness as constructed and contingent on changing social and cultural perceptions and practices.