Oliver is born in a workhouse in a small town about 70 miles from London, England in the early part of the 19th century. His mother dies almost immediately after his birth. Nobody knows who she was, but the doctor notices that she wasn't wearing a wedding ring (scandalous!).
Oliver is brought up at a "child farm" in the country until he is about eight years old. At this point, the parish officials running the child farm decide it’s time for him to start working, and they send him back to the workhouse. But Oliver commits the unpardonable offense of asking for more food when he is close to starving, so the parish officials offer five pounds (a pretty good amount of money) to anyone who’s willing to take Oliver on as an apprentice. The parish officials eventually send Oliver off with a coffin-maker.
At the coffin-maker’s shop, Oliver isn’t treated much better than he was at the workhouse or the child farm. The coffin-maker, Mr. Sowerberry, isn’t so bad, but his wife, Mrs. Sowerberry, and the other apprentice, Noah Claypole, have it in for Oliver from the start. Oliver gets in trouble for knocking Noah down (he totally had it coming). After being abused some more, Oliver decides to set out for London on foot.
When he’s almost there, he runs into an odd-looking young man named Jack Dawkins (better known as The Artful Dodger). The Dodger buys him lunch and offers to introduce him to a "gentleman" in London who will give him a place to stay.
Once in London, it quickly becomes clear to the reader (but not to Oliver) that the Dodger and his friends are an unsavory bunch. The old "gentleman," Fagin, trains kids to be pickpockets, and then he sells off what they steal. But Oliver doesn’t realize what’s up until he’s actually out with the Dodger and another one of the boys, named Charley Bates. Oliver sees the pair steal the pocket handkerchief out of a nice-looking old man's pocket. When Oliver turns to run away, the nice-looking old man sees him run and yells, "stop, thief!"
Oliver is tackled in the street, but by then the nice old man (his name is Mr. Brownlow) has taken a better look at him. He realized that Oliver looks too sweet and innocent (and terrified) to be a pickpocket. In fact, Oliver isn’t so much a pick-pocket as he is a very sick little boy. So Mr. Brownlow takes Oliver home and cares for him until he’s well.
Unfortunately. Fagin, the Dodger, Nancy (a prostitute), and Bill Sikes (another criminal) are worried that Oliver will rat them out to the police, so they keep a watch on Brownlow’s house. One day, when Brownlow entrusts Oliver with some money and an errand to run in the city, Fagin and the criminals nab the poor kid once again. Nancy feels guilty and steps in to defend Oliver when Fagin tries to smack him around.
Fagin keeps Oliver shut up in a dreary old house for weeks, all the while still trying to turn him into a criminal. How long can a nine-year-old hold out?
Not long afterwards, Bill Sikes and another thief say they need a small boy to help them break into a house outside of London; Fagin volunteers Oliver. The plan goes awry when the servants of the house wake up and catch Oliver in the act of sneaking in. The servants don’t realize that Oliver is there against his will, and was actually about to wake up the household to warn them about the robbers. So poor Oliver takes a bullet and is left behind when the rest are all running away.
Fortunately, Oliver is picked up by the people who shot him, a family that turns out to be as nice as Mr. Brownlow. They become Oliver’s caretakers.
Meanwhile, Fagin is at his wits’ end wondering what happened to Oliver. He lets slip that a mysterious man named Monks offered to pay him hundreds of pounds to corrupt the young boy. Nancy pretends not to know what’s going on, but secretly resolves to help Oliver, and to figure out why Monks is so keen on having Oliver turn to crime.
While Fagin and the criminals distress, Oliver learns to read and write with his new friends, the Maylies. He's also reunited with his first friend, Mr. Brownlow.
Fagin and his gang are still trying to track Oliver down. Monks has managed to get hold of – and destroy – one of the few surviving tokens of Oliver’s parentage. Nancy finds out about it and gets in touch with Rose Maylie to warn her about Monks’s plot with Fagin. Unfortunately for Nancy, Bill Sikes (her lover) finds out about it and brutally murders her. Sikes tries to escape, but he’s haunted by what he’s done. Eventually, he's killed while trying to escape from the police: he falls off a rooftop while he’s trying to lower himself down, and inadvertently hangs himself.
Meanwhile, Mr. Brownlow has managed to find Monks. Mr. Brownlow was an old friend of Monks’s father and knows all about him. As it turns out, Monks is actually the older half-brother of Oliver, and was trying to corrupt Oliver so that he’d secure the entire family inheritance himself. Monks chooses to admit to everything rather than face the police.
Oliver ends up with what’s left of his inheritance, is legally adopted by Mr. Brownlow, and lives down the road from the Maylies. Everybody lives happily ever after. Except for Fagin, who is arrested and hanged, and Monks, who dies in prison.