Fearless African explorer ... world-renowned humanitarian ... Irish rebel ... gay martyr. Roger Casement confronted evil and danger on three continents, and won every battle but the last. As British consul in King Leopold's Congo, Casement exposed the horrors that Joseph Conrad would immortalize in "Heart of Darkness." Just four years after being knighted for his work, Casement was convicted of treason for his role in Ireland's Easter Rising. Widespread sentiment for clemency collapsed when the British government circulated his private diaries, revealing an active gay sex life. Casement was...