Old Martin Chuzzlewit travelling in Wiltshire with his companion Mary Graham, is suddenly taken ill. Lying at the Blue Dragon Inn, he finds himself surrounded by grasping relatives anxious to inherit his money. They have learnt that his grandson, Young Martin has been disinherited. His cousin Seth Pecksniff, secretly takes young Martin on as an apprentice with hopes of making a match with one of his daughters (Charity or Mercy). Young Martin joins the simple Tom Pinch as an apprentice. Pecksniff is summoned to London lodging with his daughters at Mrs Todgers' boarding house. Old Martin confides to Pecksniff that against his wishes young Martin intends to marry Mary Graham.

Seth Pecksniff returns to Wiltshire to carry out Old Martin Chuzzlewit's orders. Young Martin is expelled from his position and resolves to seek his fortune in America, a country which he thinks will need young architects. Mark Tapley from the Blue Dragon Inn volunteers to act as his unpaid servant until his fortune is made. Tom Pinch is upset that Young Martin is leaving and he gives him his last half sovereign. Young Martin has a tearful farewell with Mary, they pledge their love and she gives him a diamond ring.

Jonas Chuzzlewit gives his father a lavish funeral, then, encouraged by Pecksniff returns with him to Wiltshire to pay further attention to Charity. Anthony's ancient clerk, Mr Chuffey, is left in the care of Mrs Gamp, a "specialist nurse". To Charity's dismay and anger, Jonas proposes to Mercy who, after much teasing, accepts. Old Martin Chuzzlewit and Mary Graham turn up unexpectedly at Pecksniff's, and the latter attempts to insinuate Jonas back into his uncle's favour.

Jonas seeks to insure the life of the new Mrs Chuzzlewit, (Mercy) and meets Montague Tigg who has undergone a transformation to become the director of the fraudulent Anglo-Bengalee Disinterested Loan Company, and changed his name to Tigg Montague. He persuades Jonas to become a shareholder in his company and then commissions an investigation into his past. In Wiltshire, Charity plans to leave her father and live independently in London. Meanwhile Pecksniff is seeking to take advantage of an increasingly senile Old Martin and invites him and Mary to move into his home.

On arriving in London, Tom Pinch accidentally meets Mercy and is shocked to see how much she has changed since her marriage. Jonas however is also fear-ridden, as Tigg Montague's investigations have disclosed some damning information about him. Tigg attempts to blackmail Jonas into investing more money in his business, but Jonas panics and attempts to flee to Rotterdam with his wife. Tigg has put a private detective (Nadgett) on his trail and he catches Jonas at the docks. Jonas is then forced to agree to try and trap Pecksniff into investing in the company and Tigg and Jonas make a trip to Wiltshire.

Final episode of the adaptation of the Dicken's novel. Jonas is still hounded by Montague Tigg. He constructs an elaborate alibi before travelling to Wiltshire and under cover of darkness, he waylays Tigg and murders him. Back in London, Jonas is accused of the murder of his father, but Chuffey reveals that Anthony knew he intended to kill him and that he died of a broken heart on discovering his son's plot. Tom Pinch finds that his mysterious benefactor is none other than Old Martin Chuzzlewit who now seeks Tom's help to call a family conference. When Nadgett and the police come to arrest Jonas for the murder of Tigg he commits suicide rather than face a trial.