Summary
In the wake of their father's death, Tip and Amy Dorrit have returned to London, where Tip has fallen ill and Amy is nursing him. Fanny is desperately bored with her husband and lack of social life, since both mourning and the fact that she is pregnant make it inappropriate for her to be mingling in society. One night, Fanny and Edmund are surprised by a visit from Mr. Merdle, who seems to be behaving strangely. He borrows a penknife from Fanny and leaves in a hurry. That night, a well-respected physician is contacted to come to the public baths, where he finds the body of Merdle, who has committed suicide. The news spreads quickly, followed by a second piece of shocking news: Merdle was a fraud, and everyone who invested with him has now lost their money.
Since Arthur invested money from his and Doyce's company, this is a serious loss to him. Despite legal advice to the contrary, Arthur takes full moral and financial responsibility for the losses. This means he is arrested for debt, and imprisoned in the Marshalsea Prison. There, John Chivery makes a show of being courteous but finally bursts out with frustration, explaining that Amy was in love with Arthur. Arthur is shocked, and realizes that he loves Amy as well.
Arthur receives visits and support from friends like the Plornishes, and one day, he is visited by Cavaletto/Mr. Baptist and Blandois/Rigaud. Cavaletto has successfully found his former master and brought him to Arthur as requested. Blandois explains that he is trying to sell something to Mrs. Clennam but she has been refusing to meet his price. Due to his imprisonment, there's little Arthur can do, but he writes to his mother telling her to pay Blandois off in order to clear her name. Arthur also confronts Blandois about the fact that Blandois was being paid to spy on the Gowan family by Miss Wade. Mrs. Clennam responds that she will get Blandois his money, but that she wants nothing to do with her son now that he is in jail.
Arthur starts to languish and fall ill in prison, and at the peak of illness, he is startled to have Amy appear and start nursing him. She explains that she came as soon as she heard he was in prison and that she wants to use the money she inherited from her father to pay off his debts. Arthur is too ashamed to accept the offer, and even tells Amy not to come visit him much because she is too good for the prison.
The time comes for Blandois to collect his payment, so he goes to see Mrs. Clennam, accompanied by Pancks and Cavalletto. In front of them as well as Flintwinch and Affery, Blandois demands a large sum of money, but Mrs. Clennam says she doesn't have the money, and doesn't know what he's blackmailing her over. Blandois begins his story with familiar information: the marriage between Mrs. Clennam and Arthur's father was engineered by his uncle, Gilbert Clennam. Blandois then forces Mrs. Clennam to admit shocking new information: she is not actually Arthur's mother. After growing up in an intensely strict and religious household, she married Arthur's father expecting he was the same way, but was horrified to eventually learn that he had a child from a secret marriage which he had hidden from his uncle out of fear. In order to resolve the situation and punish the individuals whom she saw as guilty sinners, she took Arthur away from his mother and raised the child herself. She sent her husband away to China so that he would be separated from the woman he actually loved.
There's also more to the story: Gilbert Clennam eventually came to feel guilty about the situation and left a sum of money to Arthur's birth mother in his will, as well as a sum to any daughters of her patron—who turns out to have been none other than Frederick Dorrit. Because Arthur's mother was dead, and Frederick Dorrit did not have a daughter, but did have a niece, all this money should have gone to Amy Dorrit. However, Mrs. Clennam hid the revised will and justified herself by planning to leave the money to Amy after her own death. Flintwinch knew all of these secrets, and over time, he got more and more fed up with Mrs. Clennam deceiving her son. Flintwich gave the will to his twin brother, who took it with him to Antwerp where he became friends with Blandois. After his death, Blandois took the papers, which is how he now is using them to blackmail Mrs. Clennam.
Blandois is out of patience, and explains he has already left copies of the documents with Arthur and Amy, with instructions on when to open them. If he is not paid that night, the secret will be revealed. Aghast, Mrs. Clennam leaps from her chair and heads to the prison on foot, pursued by Affery and Flintwinch.
Analysis
In the penultimate section, two huge secrets are revealed with consequences for virtually all of the characters. Both secrets involve deliberate deceptions: Merdle is actually a fraud, and Mrs. Clennam is not actually Arthur's mother. The first secret is more public in nature, and therefore revealed in a more public way. Just as gossip and rumors drove the enthusiasm for investing in Merdle's scheme, the same forces spread the word of his death, and the crimes he committed. The highly public reaction reveals how quickly the world will turn on a man it had previously adored: all of a sudden, everyone seems to remember the things they always mistrusted about Merdle. The revelation and the way he almost immediately ceases to be regarded as a gentleman mirrors what could have happened if Mr. Dorrit's secret had ever come out.
Merdle's secret has very real economic implications. Arthur responds by taking total personal responsibility, which he was not legally required to do, and which Rugg and Pancks also don't think he was ethically compelled to do. However, Arthur feels a lot of shame for having made a bad business decision and impacted Doyce as well as himself. He has always been worried about the integrity of the Clennam family business and refuses to perpetuate a family history of shady business dealings. Nonetheless, ending up in prison is depressing and humiliating, especially after his mother responds by disowning him. Arthur now can't do anything to help his mother in whatever plot Blandois is using to exploit her.
However, while his imprisonment disempowers him in many ways, it also grants Arthur clarity about something to which he has long been blind: he is able to realize that he is in love with Amy. Up until this point, several things have made it impossible for Arthur to recognize this reality. At first, he was distracted by his attraction to Pet, and he was also preoccupied with the idea of "saving" Amy. He could only see her as a vulnerable and child-like figure, not a grown woman for whom he could feel desire. Then, as soon as Amy's fortunes reversed, she moved out of his reach, since as the wealthy daughter of a newly rich family, she was now above his social station. Once he's in prison, conventions around social expectations fall away, and Arthur can see clearly that he and Amy loved each other because they shared values and interests.
At first it seems like Arthur's imprisonment will lead not only to the recognition of his true feelings, but also the chance to actually act on them. Amy all but proposes to him as she nurses him and offers to give him any money he might need to pay off his debts. While Amy often seems like a stereotype of the passive and angelically virtuous Victorian female character, this suggestion shows her being quite assertive and independent. Arthur physically needs her due to his illness, and he also needs her economically, reversing the power dynamic that was initially established between the characters. Arthur, however, cannot accept the full vulnerability of this position, and thus turns down her offer. Nonetheless, the two continue to see a lot of each other, and their relationship clearly has a new dimension. Partially this stems from Arthur's increased self-awareness, but also from Amy's new self-confidence. She has seen the world, learned to be more independent, and is now much more capable of making the choices that will make her happy. With her father and uncle dead, and her sister married, she is also no longer responsible to anyone from her biological family.
While Arthur is discovering the clarity of honesty and self-awareness, Mrs. Clennam's web of carefully-constructed lies finally starts to unravel. She learns she has been betrayed by Flintwinch, who has long been the one person she trusted with her secret. The revelation of the family history connects to themes evident in other subplots of the novel: the dangers of a loveless marriage, the need to try and control others, and a lack of self-awareness blinding someone to their moral failings. Even as her secret is revealed, Mrs. Clennam defends her choices and feels justified by a divine mission to prosecute sinfulness. She does not regret that she has allowed Amy to live in poverty and suffering for years, or that she kept Arthur away from a mother who presumably would have loved him dearly. She does, however, react with horror to the news that Arthur is on the brink of learning her secret. By rising from her wheelchair to run to the prison, Mrs. Clennam symbolically bursts free from the web of lies she has spun over the years.
