The story of communism holds a malign fascination for me, so I've always made it my business to stay informed. However, there is much dross out there, and Communists are nothing if not good propagandists. So I've assembled a list of books on various topics to make it easier to know what *really* happened.
For broad strokes, one interesting recent work is "Heaven on Earth - the Rise and Fall of Socialism" by Joshua Muravchik. In the words of a cover blurb, "Socialism was man's most ambitious attempt to supplant religion with a doctrine claiming to be rational and 'scientific'". Muravchik follows the different strands wherever they lead through the present day.
Another interesting survey is "The Black Book of Communism". The authors trace the deadly legacy of Communism around the world in unsparing terms.
Some countries' experiences were particularly interesting. In "Spain Betrayed" we find out much about the Spanish Civil War which the left would prefer to have hidden. "A Twilight Struggle - American Power and Nicaragua 1977-1990" is about those left-wing darlings, the Sandinistas. "The Great Terror" is about the Russian experience. And "Hungry Ghosts" is set in China and talks of Mao's famines - they were so severe that peasants were driven to eating babies.
For the US experience, "Not Without Honor" is about American anticommunism, warts and all. "Hollywood Party" is about Communist efforts to take over movie studios. The legend of the Hollywood Ten is so deeply entrenched that diehards felt it necessary to disrespect Elia Kazan at his lifetime achievement award half a century later.
That great leftist bogeyman Joe McCarthy deserves an item of his own. He led a charge against Communists in government that was resisted with partisan fury by the long-incumbent Democrats. For a while he was a popular politician who owned an issue of great public concern. However, he had a drinking problem and he did not know how to handle that then-new technology called television. These shortcomings led to a loss of public support and subsequent censure by the Senate when his own party was in the majority. But in fact the US government was riddled with Communists and sympathisers, to the point where FDR dumped then Vice President Henry Wallace in favor of Harry Truman. Read more about it in "Joseph McCarthy: Reexamining the Life and Legacy of America's Most Hated Senator" Challenge question - can you name anyone McCarthy accused of being a Communist who was not a Communist?
Communists learned a long time ago that they could not be truthful and still be successful - truth was defined as what served the Party. So Gus Hall's Communist Party of the US always denied they were associated with the USSR, Alger Hiss still has defenders, and prominent anticommunists are smeared at every opportunity. But the truth will out, and all sorts of interesting revelations emerged after the Cold War when Soviet archives were opened to researchers. This information led to books such as "The Secret World of American Communism", "The Soviet World of American Communism", and "Venona - Decoding Soviet Espionage in America".
For a more personal look, IMO the best book is "Witness", by Whitaker Chambers. More contemporary books are "Commies" by Ronald Radosh and "Radical Son" by David Horowitz. You can also catch up with Horowitz here.
That ought to keep you busy for a while. Failing that, here and here are Amazon lists with much more.