Oliver Twist's mother dies after the birth of her child in a workhouse. The infant's father is unknown, and the orphan is placed in a private juvenile home. After nine years of mistreatment, the boy is returned to the workhouse for even more abuse. After representing his fellow sufferers in an attempt to get more food, Oliver is punished and is apprenticed to Sowerberry, an undertaker. Noah Claypole, a charity boy working for Oliver's master, goads Oliver to rebellion, for which Oliver is savagely flogged. Consequently, Oliver runs away and heads for London.
Near London, Oliver joins company with John Dawkins, The Artful Dodger, a questionable character who brings the boy to Fagin, the ringleader of a gang of criminals. Instructed in the "art" of picking pockets, Oliver goes out with Charles Bates and the Dodger. His companions pick an old gentleman's pocket and flee, and Oliver is arrested for their offense. At the police station, the terrified boy is cleared by the testimony of the bookseller who witnessed the theft. Oliver collapses and is taken home by Mr. Brownlow, the victim of the crime.
While Oliver recovers at his benefactor's home, Brownlow is puzzled by the resemblance between Oliver's features and the portrait of a young woman. Fagin is apprehensive and furious at Oliver's rescue. Nancy, one of his trusty retainers, is set on the boy's trail as the gang shifts headquarters.
Mr. Grimwig, Brownlow's friend, has no faith in Oliver, so Oliver is sent on an errand to test his honesty. The boy is recaptured by Nancy and her friend Bill Sikes, a vicious lawbreaker. Oliver is restored to Fagin, who holds him in strict captivity for a while. In the meantime, Bumble, a minor parish official from Oliver's birthplace, answers Brownlow's advertisement inquiring about Oliver. Bumble turns Oliver's benefactor against him by grossly misrepresenting the boy's history and character.
Eager to get Oliver completely in his power by thoroughly involving the child in some crime, Fagin convinces Bill Sikes to use Oliver in a major burglary that is being planned. Sikes takes Oliver westward through the city to a rendezvous near Chertsey with Toby Crackit.
At the house that is to be burglarized, Oliver is hoisted through a small window. The occupants are aroused and in the resulting melee, Oliver is shot. The robbers run off with the wounded Oliver but abandon him in a ditch.
In the workhouse, Sally, the old pauper who attended Oliver's mother, is dying. At her urgent request, Mrs. Corney, the matron, sees the old woman alone before she expires. Immediately thereafter Bumble and the matron agree to marry.
Fagin is greatly upset when Toby Crackit returns alone. Fagin makes anxious inquiries about Sikes. He then has an ominous meeting with a person called Monks, who is angry with Fagin, who he claims has failed in his obligation to ruin Oliver by tricking him into a lawless life
When Oliver regains consciousness in a ditch, he stumbles to the nearest house, which proves to be the site of the attempted burglary. The owner, Mrs. Maylie, takes the boy in and protects him with connivance of her doctor, Mr. Losberne. The boy is taken to a cottage in the country, where Mrs. Maylie's niece Rose suffers a near-fatal illness. In the town inn yard, Oliver encounters a repulsive stranger who later spies on him with Fagin. Rose rejects the proposal of Mrs. Maylie's son, Harry, but he does not accept her refusal as final.
Monks meets the Bumbles and purchases a locket that Mrs. Bumble redeemed with a pawn ticket that she took away from the dead Sally, who had received the pledge from Oliver's dying mother. The trinket contains a ring inscribed with the name "Agnes"; Monks drops it into the river.
Nancy, who sympathizes with Oliver, nurses Sikes until he regains his "natural" meanness. She drugs the man and slips away to Hyde Park for a secret meeting with Rose Maylie. Nancy tells Miss Maylie everything that she has learned by eavesdropping on Fagin and Monks on two occasions. The two rogues are plotting the destruction of the object of Monks's inveterate hatred — his brother Oliver. Mr. Brownlow, who has been absent from London, reappears and Rose tells him Nancy's story. Harry Maylie, Grimwig, and Mr. Losberne are also briefed on what Nancy has learned.
Noah Claypole and Charlotte, Sowerberry's maidservant, hide out in London after she has plundered the undertaker's till. They are discovered by Fagin, and Noah is employed to visit the police station to bring back information about the Dodger's indictment as a pickpocket. Because of her suspicious behavior, Fagin then assigns the sneak to spy on her. Nancy has a midnight meeting with Rose and Brownlow on London Bridge. Nancy informs Brownlow how he can corner Monks. Noah hears everything and immediately reports his findings to Fagin.
Fagin waits up for the marauding Sikes and provokingly discloses Nancy's double-dealing. Sikes promptly goes home and bludgeons her to death. After wandering in the country for a day, haunted by his evil deed, the murderer returns to London.
Mr. Brownlow has seized Monks and taken him to his home. The resultant disclosures clear up many mysteries. Brownlow had been engaged to the sister of his friend Edwin Leeford, Monk's father. While yet a mere boy, Leeford was forced into a bad marriage. The couple had only one child — Monks — and separated. Leeford became attached to a retired naval officer's daughter, Agnes Fleming. But Leeford died suddenly in Rome while looking after an inheritance. His wife had come to him from Paris just before his death. At the time, Agnes was expecting a child — the future Oliver Twist. Before leaving for Italy, Leeford had left the girl's picture with his friend Brownlow.
On account of the striking similarity between Oliver's face and Agnes Fleming's, Brownlow has been searching for Monks since the boy's disappearance. With the help of Nancy's discoveries, Brownlow has learned all about the destruction of Leeford's will, the disposal of the identifying trinket that Oliver's mother possessed, and Monks's vindictive conspiracy with Fagin to destroy the innocent boy. Faced with these revelations and a reminder of his complicity in the murder of Nancy, Monks comes to terms in return for immunity on the condition that Monks make restitution to his brother (Oliver) in accordance with the original will.
Toby Crackit and Tom Chitling have taken refuge in a crumbling building amid the ruins of Jacob's Island, in an inlet on the south side of the Thames. Fagin has been arrested, along with Claypole, while Chitling and Bates escaped. An unwelcome addition to the group is Bill Sikes, who is being tracked down. Charley Bates turns against the killer and raises an alarm to guide the pursuers. Attempting to escape from the house top, Sikes falls and is hanged in his own noose.
Oliver returns to the town of his birth with Mrs. Maylie, Rose, and Mr. Losberne. Brownlow follows with Monks. Monks confirms what he has already declared in writing. The past history of the two half-brothers is recapitulated. Their father's will left the bulk of his fortune to Agnes Fleming and her expected child. The Bumbles admit their part in the affair after being confronted with Monks's confession.
A new disclosure concerns Rose, who is of uncertain origin, although recognized by Mrs. Maylie as her niece. Rose is in reality the younger sister of Agnes Fleming, hence Oliver's aunt. Harry Maylie has repudiated his station in life to become a village parson, so the way is cleared for the young couple's betrothal.
Fagin is found guilty and sentenced to be hanged. While in prison awaiting execution, he disintegrates into a state of unrepentant maliciousness, but on his last night, he is visited by Brownlow and Oliver. Regaining some semblance of humanity, he reveals the location of some papers relevant to Oliver's interests.
For testifying against Fagin, Claypole is pardoned, and he and Charlotte live by disreputable means. Charles Bates reforms and becomes a herdsman. The other leading members of Fagin's gang are transported from England. In accordance with Mr. Brownlow's recommendation, Oliver shares his fortune with Monks, who nevertheless later dies in prison, destitute.
Rose and Harry Maylie are married, and Mrs. Maylie lives with them. Brownlow adopts Oliver and they settle near the parsonage, as does Mr. Losberne.
The Bumbles lose their positions and become inmates of the workhouse where Agnes Fleming died after giving birth to Oliver Twist.