A few days later Nell and Letty are going to a masquerade at Chiswick, outside London and are held up by highwaymen. Letty in spite of her lively nature is scared but Nell realises that it is Dysart and calls him on it. Dysart realises that he was wearing a ring which his mother gave him, and calls off the joke.
He tells Nell and Letty that he was not trying to rob them but to find a way of helping Nell by stealing one of her ornaments which he could then sell to raise the money for paying the dressmaker. But now the plan's failed. Nell speaks to her dressmaker who says that she must have the money, because she is leaving England.. and retiring.
Letty is upset because her suitor Jeremy approaches Giles and asks him if he can have his permission to marry her, and take her to Brazil where he believes he may be posted soon. Giles says no, his half sister is only 17 and is too young to marry and go so far away... and then wonders if he is doing the right thing. Letty is furious at her brother's refusal to let her marry, and becomes very sulky, which makes life difficult for Nell. She believes that while Letty is very young, she is truly devoted to Jeremy Allandale.. and she tries to argue gently with her husband on the issue which causes more tension between them. He is irritated at her taking up Letty's cause, and feels that since the argument over money, Nell seems withdrawn from him.
Nell is feeling increasingly miserable as she is at odds now with Giles and cannot find a way to talk to him. Then to her horrified amazement, she gets a note from her brother to say that he has hit on a way of sorting out the money problem.. and then finds that a very expensive emerald and diamond necklace is missing from her jewels. The necklace is an heirloom which Nell finds too ornate and rarely wears.. but she cannot believe that Dysart would be such a fool as to steal it to help her. Her dresser Sutton has discovered its disappearance and Nell, frightened, tells her that she herself took it to the jewellers to have a catch repaired.
She cannot decide what to do, when Dysart comes to see her and gives her the money to pay the dressmaker. In horror, she asks him why he took the necklace.. and he angrily tells her that he would never do such a thing, that he has won the money on a horse race... He borrowed from one of his friends, and won a stake racing cockroaches... and then put it all on a horse which brought in enough to help him out and to pay Nell her money. But their big problem is how to tell Giles that a valuable necklace is missing.....
When she tells Giles he tells her that he has the necklace.. that it was brought to him by a jeweller who realised that it was an heirloom.. and offers it back to him. Giles pays for it and takes it back, having learned that a veiled lady brought it in to sell a couple of days ago. Nell is hurt that he could think she would sell it, and rushes out of the room. Giles then feels guilty and tries to go after her, but he does not know what to make of what has happened. Then Nell finds that Letty has disappeared, she has taken a bag of clothes with her and her maid is finally pushed to admit that her young lady has left the house. Nell goes to Letty's aunt, Mrs Thorne, who is horrified that her niece has been behaving so wildly. Nell then goes to Mr Allandale's lodgings and finds that a young lady had called to see him and that he has gone away from his rooms... Nell thinks that Letty must have sold the necklace to get money and persuaded Allandale to elope. She wonders how to protect her sister from the folly of a Gretna Green Marriage. She goes back to her own house to try and work out a plan, and Giles is there, and he embraces her. He tells her he realised that she would never have sold the emeralds but Letty would. Before more can be said, Mr Allandale arrives with an indignant Letty in tow. He tells Giles that Letty had come to him, hoping to get him to run off with her, but he took her to the suburbs to see his mother, who is a very strict lady. This quelled Letty and he has brought her back to her brother. Giles tells him that he will give permission for the marriage, as Letty clearly loves him so much - and he loves her and will put up with her wilful ways. He sends his sister to bed and takes Nell in his arms and tells her he loves her and never loved Lady Orsett, his mistress. She tells him that she owed money to her dressmaker and felt she could not tell him, then that she loved him...it woudl look like cream pot love. They agree to embark on a new and happier stage of their marriage.