Emma Healey’s novel Elizabeth is Missing (2014) offers a poignant exploration of memory loss, portrayed through the lens of Maud, an elderly woman struggling with dementia. As Maud’s cognitive decline intensifies, the novel becomes a window into the fragmented and unreliable nature of her memories, inviting readers to experience the world through her distorted perception. This paper examines how Healey uses Maud's unreliable narration to explore key themes such as memory, identity, time, and the human need for coherence. By juxtaposing Maud's cognitive deterioration with the concept of hyperthymesia, an exceptional ability to recall autobiographical details with unparalleled precision. The study draws attention to the contrasting ways in which memory impacts an individual's sense of self. Hyperthymesia, which often proves to be as psychologically burdensome as it is remarkable, provides a critical lens through which to understand the implications of both memory loss and memory excess in shaping identity. Through a combination of literary analysis and cognitive theory, this paper situates Elizabeth is Missing within broader discussions of memory’s role in selfhood and narrative reliability. By investigating how memory functions as both a source of emotional pain and a critical aspect of identity construction, the study engages with larger questions of how human beings use memory to navigate their lives, maintain personal continuity, and make sense of their pasts.