I'm looking for something that covers the ideological and historical underpinnings of communism.  Especially anything that addresses the ideological and philosophical influences on the people who devised it.

One has to distinguish between the thought of Marx and Engels, on one hand, and later so-called Marxist-Leninist lines of thinking, then the abomination of Stalinism.

In other words, what we call communism is not a unitary phenomenon.

Marx never described how a socialist/communist state would function. As a result, most revolutionaries developed their approaches around revolutionary Leninism and the oppressive statism of Stalin. To be clear, they are not  unrelated.

Read the Communist Manifesto by Marx.  Good biographies of key players like Lenin, Trotsky and Stalin give clear views of their ideological development according to both Marxist and non-Marxist lines.

Lenin by Robert Service and Stalin: The Paradoxes of Power by Stephen Kotkin are good starting places.

For a basic primer on Russian revolutionary history a good place to start is Orlando Figes' Revolutionary Russia 1891-1991, followed by his A People's Tragedy which deals specifically with the 1917 Russian Revolution.

Hope this helps. A  great body of historical literature has developed on these topics since 1989.

(You can't get around the Germans and, most especially, the Russians, in exploring this topic.)

@Terlinguachili

Good recommendations.

For a little context, I'm considering writing my own book and this reading would be the start of my research into the subject.  I have a hypothesis that whatever communism is, it isn't what it presents itself to be.  I think there's something deeper under the surface that's persistent, and it calls itself something different when whatever it's calling itself at the moment starts getting bad PR.  We see that manifested in recent history with postmodernism.  Whatever postmodernism presents itself to be, if you scratch under the surface of a postmodernist you quickly find a Marxist.  Communism has increasingly bad PR, ergo, postmodernism.  So the questions that occur to me is, 1) is this is a long term historical phenomenon, 2) what is communism really? (that is, what is under the surface beyond what it presents), 3) before it was called communism, what did it call itself, and 4) how far back in history does this go?

I strongly suspect the answer to #1 is yes.  I have some thoughts about #2, but I'd rather dig into it deeply.  By answering #3 in one succession after another, you get the answer to #4, and I suspect the answer to #4 is something like "since history has been recorded."

The most pervasive current influences seem to be deconstruction theory and critical theory, which are related. They give rise to the concepts of intersectionality, LGBTQ issues and racial identity. They underpin what we call cultural Marxism.

The epic change was at the time of and after the French Revolution. For instance, give Thomas Payne another read.

That revolution let the genie out of the bottle regarding philosophy and politics.

Good luck with your research.