Arthur Conan Doyle called Machen a genius; Oscar Wilde, W.B. Yeats and H.G. Wells admired him. His classic horror novel The Great God Pan, which both shocked and delighted contemporary readers with its dark portrayal of sexuality and its alluring villainess, has been favourably compared to Stevenson's Dr Jekyll and Mr Hyde; his The Secret Glory changed John Betjeman's life; while his masterpiece The Hill of Dreams, located in his beloved Gwent, has been called the most beautiful book in the English language. It is a testimony to his writing skill that through one short story, The Bowmen, he once made thousands believe that angels had appeared at the Battle of Mons, sparking a whole series of myths. Largely neglected by critics and biographers, Machen has remained an inspiration to those readers who have sought him out, and current admirers include cellist Julian Lloyd Webber and TV personality Barry Humphries. Mark Valentine's biography, the first in many decades, provides a much needed re-examination of Machen's varied and fascinating career.