First published in 1895, Arthur Machen's 'The Novel of the White Powder' is a masterwork of Victorian horror that explores the dangerous intersection of forbidden knowledge and bodily corruption. Through the testimony of Miss Leicester, the story chronicles her brother's descent into unspeakable transformation following the ingestion of a mysterious white powder prescribed by their family physician. Machen's narrative skillfully blends the mundane world of London domesticity with intimations of ancient, occult evil, culminating in a revelation that challenges the boundaries between the material and supernatural. Readers should expect deeply unsettling psychological deterioration, a sophisticated epistolary conclusion, and Machen's characteristic exploration of how hidden forces of corruption operate beneath the surface of civilized society.