Two months before he died, John Keats claimed he had been poisoned. Although most scholars and biographers have attributed Keats's fears of persecution, betrayal, and murder to consumptive dementia, Keats's suspicions had begun long before 1820 and were not without some justification. In this article, the author talks about the death of John Keats, one of the best-loved poets in the English language, which remains a mystery. She also describes how mystery becomes a key to understanding both his poetry and his life and not just a literary whodunit.