Where to begin with the Second World War? Its awful scale swamps any single story. In Surviving Katyn (Oneworld, £10.99; Tablet price £9.89), Jane Rogoyska records one appalling fact and how it was saved from obscurity by the efforts of a few individuals. In the spring of 1940 the Soviet secret police murdered 22,000 Polish prisoners of war in the forests of Katyn – and this atrocity is at the centre of the book. Rogoyska follows the survivors in their battle against Stalinist obfuscation and Western apathy.