After a bloody civil war that followed the end of World War II, Mao Zedong hoisted the red flag over Beijing's Forbidden City in 1949. 

Instead of liberating the country, the communists transformed China into one of the worst tyrannies of the twentieth century, sending at least five million civilians to an early grave and bringing misery to countless more. 

Frank Dikötter talks about his latest book, The Tragedy of Liberation, which draws on newly opened party archives, interviews and memoirs to interweave the stories of ordinary men and women with the brutal politics of Mao's court. It casts new light on the foundations of one of the most powerful regimes of our times.