Jurgis Rudkos is a Lithuanian immigrant who has come to America with his fiancee Ona and their families to seek the good jobs advertised in his poverty-stricken homeland. It's tricky for people who don't know English or the local customs to get around, but finally they make it to the Packingtown district of Chicago, and a countryman who can give them advice. Soon, the adults of the family have jobs in the slaughterhouses and related businesses, and they move into a house together. Times are tough, but if everyone works hard and saves their money, things will surely get better. 
 But the naive immigrants have no idea just how much worse things can get in a world where the law of the jungle prevails, and each is pitted against each. 
 This (in)famous novel was originally published as a serial in The Appeal to Reason and One-Hoss Philosophy, Socialist publications. In order to get it published as a book by a major publishing house, Mr. Sinclair had to tone the story down quite a bit, and it was still considered immensely shocking. The version I read is called "uncensored" but would more rightly be called "unexpurgated", with the text as it was written for the serial. 
 An introduction by Kathleen De Grave explains what was cut for the 1906 version, and how that affects the tone of the story. For example, it's left in that the slaughterhouse workers spent their lunch time in saloons, but left out is the explanation that there were no other places to get food in walking distance of the plants. If you wanted to have a warm place to eat, you must buy alcohol. 
 In either version, this is a depressing story. The odds are stacked against Jurgis and his family from the very beginning, with grifters ready to swindle the immigrants any way they can, from phony officials asking for fees that don't exist to "pesticides" that are completely inert. One of the central heartbreaking examples is the house the immigrants "rent to buy." It is not at all as advertised, there are fees in the lease contract that are not disclosed until well after the family has settled in, and miss even one payment, and you are out in the street. 
 Which would be fine if everyone stayed in work. But what if you get sick or injured and they fire you for missing work? What if your boss fires you because he's found someone who will do the job for two cents less an hour? What if the entire factory just closes down for a month or three? Even the relatively nice employers have no compunctions about getting rid of workers who become inconvenient. 
 And while the slaughterhouse scenes are as horrific as advertised, don't think the vegetarians are going to get away unscathed. Fruits and vegetables and milk are all adulterated, the clothing sold in the stores the poor have access to is thin shoddy (and overpriced at that!) and you can drown in the streets during the rainy season. 
 The misfortunes that Jurgis and the others undergo are all real, but probably happened to a half-dozen different families that Mr. Sinclair talked to while researching this book. Here, it's all visited on one unlucky group of immigrants, and particularly Jurgis. The rule of thumb is that if Jurgis gets a couple of pages where things are looking up even a little, the hammer is about to come down even harder, sometimes by Jurgis' own ill-considered actions. 
 While Jurgis is initially a decent man, who tries to do the right thing, by the time everyone he ever loved is dead, he is ready to chuck conventional morality. He sinks lower and lower, becoming in turns a mugger, a political operative, and worst of all, a scab worker. 
 Even when the novel ends on a hopeful note, as the Socialists gain votes (for the only way the world can be saved is to smash capitalism and adopt socialism), Jurgis himself is being carted off to prison for attacking the politically protected man who raped his wife. 
 Yes, there's (off-camera) rape in the story, and child abuse (by Jurgis!) and a fair amount of other things that could be triggery, even if you can keep your lunch down during the slaughterhouse scenes. The last few chapters are nigh unreadable for the opposite reason, as they devolve into sermons (at least one literal) on the benefits of socialism. 
 There's early 20th Century ethnic prejudice, racism and sexism on display; it's up to the reader to decide how much of it is a realistic depiction of the attitudes of the times, and how much Mr. Sinclair being unable to fully rid himself of unworthy cultural blinkers. 
 It's also worth considering how things have changed since this book was written, and how little things have changed. Too many pundits and plunderers would gladly have us go back to before "onerous" government food regulations, minimum wage laws and other protections for workers. They think that of course they would be immune to the dangers of the Jungle, but in the end, the Jungle consumes everything within it.