We really can't say it better than Joseph Conrad himself. Heart of Darkness is:
A wild story of a journalist who becomes manager of a station in the (African) interior and makes himself worshipped by a tribe of savages. Thus described, the subject seems comic, but it isn't. (source)
No—not comic at all. Set in the African Interior and based on Conrad's own experiences as the captain of a Belgian steamer, Heart of Darkness isn't much like the rousing adventure story that it could be. It's less Indiana Jones and the Ivory Traders than, well, psychological horror. And in February of 1899, readers of Blackwood's Magazine—a high-falutin' literary rag, kind of like The New Yorker—would have been treated to the first of its three parts.
Conrad is one of the most important English writers of the late nineteenth and early twentieth centuries. And get this: he wasn't even English. Conrad was Polish, and he didn't actually learn English until he was in his twenties—and after he'd already learned French. (Think about that next time you complain about having to write an essay.) His works explore the seedy underbelly of imperialism, the move in the nineteenth century for European countries to stake out claim to various far-flung parts of the world.
Heart of Darkness is set right after the Scramble for Africa, the period of the late nineteenth century when imperial powers sliced up and doled out Africa like some particularly delicious—and ivory-rich—birthday cake. None of the Western countries really come off looking good in this whole debacle, but Belgium, unfortunately, looks particularly bad. They were after the valuable ivory hidden away in the African Interior, and they weren't afraid to brutalize and oppress the Africans in order to get it. Heart of Darkness follows the disturbing journey of English ivory-trading agent Marlow, who, working for a Belgian company, travels into the jungles of Africa in search of a mysterious man named Kurtz who appears to have (1) become a god-like figure, and (2) gone totally mad.
But Heart of Darkness is much more than a story about a trip up the river. It's a searching exploration of difference: of good and evil, black and white, sanity and insanity. In the end, what we're left with is … nothing. Really. Most contemporary critics agree that the novel is about the essential emptiness at the core of humanity—and language. That's why T. S. Eliot used a quotation from the novel as an epigraph to his poem "The Hollow Men," a super important and famous literary exploration of modern life.
One last thing: in 1975, Nigerian writer Chinua Achebe spoke out against the novel. He accused it of making its point by dehumanizing Africans and reducing them to extensions of the hostile and primal jungle environment. Conrad's language was beautiful and seductive, he said—but it was wrong. Hmmm. Beautiful, seductive, and wrong. To us, that sounds a lot like how Marlow would describe Kurtz—and it's a good example of how head-twistingly complex this novel is.
Get comfy. This is going to take a while.
Have you ever rooted for the bad guy on a TV show, picked on someone smaller than you, or secretly wished that the annoying kid behind you in Calculus would get destroyed in dodgeball?
Then you, dear Shmooper, have encountered your own heart of darkness.
Okay, to be fair, it's somewhat less dark than the one Conrad shows us, probably more a light shade of gray than an inky blackness. But the point is this: people can be scary. No matter how much we like to think that we're on the side of good, the truth is that most of us are, in the right circumstances, probably capable of murder, brutality, torture, and mass exterminations. Just think of the Holocaust.
So before you start pointing fingers, take a look at your hand. See those three fingers pointing back at yourself? According to Heart of Darkness, we're all just a shrunken head away from savagery. Possible (okay, probable) racism aside, that's a truth worth caring about.