Here's a little "intro to Marxism-Leninism" list I threw together, modified a bit. It's critically missing Queer Theory, Feminist Theory, and National Liberation theory, so any additions on that matter would be excellent. I am working through intersectional theory right now, which is why it is missing from this present list, the goal is to be as straight to the point as possible.

How familiar is this person with Communism and AES? If I just want to recommend a good intro for someone with no familiarity, I usually recommend Engels' Principles of Communism and if they are anti-AES but willing to read I recommend Parenti's Blackshirts and Reds.

From there, it becomes more important to understand that Marxism-Leninism is broken into 3 major components:

1. Dialectical and Historical Materialism

2. Critique of Capitalism along the lines of Marx's Law of Value

3. Advocacy for Revolutionary Socialism

And as such, I recommend, in order:

1. Politzer's Elementary Principles of Philosophy

By far my favorite primer on Dialectical and Historical Materialism. By understanding DiaMat first, you make it easier to understand the rest of Marxism.

2. Engels' Socialism: Utopian and Scientific

Further reading on DiaMat, but crucially introduces the why of Scientific Socialism, essentially explaining how Capitalism itself preps the conditions for public ownership and planning by centralizing itself into monopolist syndicates.

3. Marx's Wage Labor and Capital as well as Wages, Price and Profit

Best taken as a pair, these essays simplify the most important parts of the Law of Value.

4. Lenin's Imperialism, The Highest Stage of Capitalism

Absolutely crucial and the most important work for understanding the modern era and its primary contradictions.

5. Lenin's The State and Revolution

Excellent refutation of revisionists and Social Democrats who think the State can be reformed, and not replaced. Also a good call to action to cap off the intro.

After reading all of this, whoever has completed these works should have a good grasp of the basics of Marxism-Leninism and be equipped to do their own Marxist-Leninist analysis, though tons of excellent and fairly critical works were dropped for the sake of limiting the scope to an intro reading list. I can make more "advanced" recommendations if they are necessary as well.