Best book for overview of 20th century communism

by Matbell87

Hi.

I've been on a documentary binge of some of the worst Communist dictators of the 20th century throughout the world: from Mao, Stalin, Pol Pot, Tito and Ceausescu.

Is there a great book with an overview over Communism - from Marx throughout the different regimes of the 20th Century. Something that goes into the intentions, what went wrong and what was Marx's original proposition

Georgy_K_Zhukov