As a rule, I'm not very keen on biographies of political leaders. They often focus narrowly on the individual, leaving an impression that they far more central to historical events than is often the case. Philip Short avoids this pitfall by using the chronology of Pol Pots life to explore the wider history of Cambodia from the 1920's onwards. Eye witness testimony is used heavily throughout the book, with a careful balance of opposing views. Unlike many biographies, this one doesn't try to "pschoanyalyse" its subject, and is all the more convincing for it.
By the end of the book, Pol Pot and his Khmer Rouge comrades come across not as monsters, but as idealists who let their dreams of a Communist utopia override the welfare of ordinary Cambodians. When the dream proved impossible to acheive they were reluctant to admit defeat, so rather than compromise they purged the middle ranks of their regime and tried to impose the same policies again. Each successive attempt ended in greater disaster, as the purges left fewer and fewer competent personnel. Crop yields spiralled downwards, and the urban population that were forced to work on the massive collective farms were the first to die.
The deaths of ordinary Cambodians were not only the result of economic mismanagement and the resultant famine. Suspected political opponents, intellectuals and the professional classes were tortured at places like the notorious S-21 prison. The motives behind the targeting of particular social groups are clearly explained in the book, the terrible result of the ideological path that Pol Pot and his colleagues followed. The way this ideology evolved is covered in great detail - the most interesting aspect of which is the strong influence of post-war French philosophy that the Khmer Rouge leadership were immersed in as students in Paris. This combined with Stalinism, Maoism, (both popular amongst French Communists) and particular Combodian traits such as the Buddhist suppression of individualism to form the Khmer Rouge version of Communism.
In conclusion, you can learn a great deal from this book, whether you're just interested in Pol Pot as an indivudual, or interested in the wider history of the Khmer Rouge and Cambodia.