Executed by the British in 1916 for treason, Roger Casement is one of Ireland's most colorful, mythologized, and controversial figures. His infamous Black Diaries, with their homosexual materials, were famously published by the Olympia Press in a suspect edition in 1959. In 1903 when he was a British consul, he left his base on the Lower Congo River and made a Conrad-like journey through the "heart of darkness" regions of the Upper Congo to personally investigate reports of alleged atrocities (Conrad found Casement to be "most intelligent and sympathetic"). His subsequent report gained him fame by exposing the appalling cruelties of the colonial and commercial regime there, and was a crucial instrument in the British government's efforts to bring about change in King Leopold's Congo Free State. He later exposed similar exploitation in Niger, Mozambique, and South America. This carefully edited work brings together Casement's report, as well as his diary of that year, with previously excised names restored and explanatory notes provided. The editors provide an overview of Casement's career and a thorough historical background to these documents. Seamus O Siochain teaches at the National University of Ireland and is completing a major biography of Casement. Michael O'Sullivan was at Dublin City University until his death in 2002.