On December 7 2006, in a Highgate Cemetery drenched with London rain, a Russian was buried within a stone's throw of the grave of Karl Marx. He was Alexander Litvinenko, Sasha to his friends, a boy from the deep Russian provinces who rose through the ranks of the world's most feared security service. Litvinenko was the man who denounced murder and corruption in the Russian government, fled from the wrath of the Kremlin, came to London, and allied...