Damned in coruscating verse by Shelley and Byron, his coffin hissed at during his funeral, Lord Castlereagh has one of the blackest reputations in British history. But as John Bew shows, this is but a half-drawn portrait. His gripping biography reveals a shy, inarticulate but passionate man; a towering political figure of implacable principles who redrew the map of Europe, fought a duel with a cabinet colleague and would tragically take his own life amid rumours of scandal and madness.