The Legal Theory Bookworm recommends Marx by Brian Leiter & Jaime Edwards. Here is a description:
The writings of Karl Marx (1818–1883) have left an indelible mark not only on the understanding of economics and political thought but on the lives of millions of people who lived in regimes that claimed (wrongly) his influence. Trained as a philosopher and steeped in the thought of Hegel, Marx turned away from Hegelian philosophy after 1845 towards a philosophy that incorporated economics and history. It is this Marx that endures and to which this outstanding introduction is devoted.
Jaime Edwards and Brian Leiter begin with an overview of Marx's life and intellectual development, including his early years as a journalist in Germany before his exile in London. They then introduce and assess the fundamental elements of Marx’s thought:
Marx’s theory of history and historical change (historical materialism)
class conflict, the state, and the Communist revolution
Marx’s theory of economics, especially the labour theory of value, and his prediction of the collapse of capitalism
the nature and role of ideology in Marx’s thought
Marx’s theory of human nature and the good life, including his arguments concerning alienation
Marx’s legacy and influence, including Western Marxism, the Frankfurt School, and “feminist Marxism”.
Including annotated further reading suggestions at the end of each chapter and a glossary of technical terms, this is an indispensable introduction to Marx's philosophical thought. It will also be extremely useful to those in related disciplines such as politics, sociology, history, and political economy.
And from the reviews:
"A tour de force. Not only the best available introduction to Marx’s thought and to post-Marx Marxist theories, but also of interest to specialists. The organization is excellent, and the writing is always clear and jargon-free. It covers all the main topics that a book on Marx should address. It is remarkably fair and balanced, sympathetic to Marx’s ideas, but also appropriately critical of them." - Allen Buchanan, Duke University, USA
"A philosophical introduction to Marx which manages to be genuinely accessible without avoiding controversy or consigning its subject to history. Edwards and Leiter bring Marx into a productive conversation with current work in the social sciences in order to develop and defend distinctive accounts of his views on history, ideology, and capitalism. A very welcome addition to the literature." - David Leopold, University of Oxford, UK