The next day, Marian is careful to intercept the delivery of the reply from the lawyer before it gets to the house. The lawyer expresses worry that what Laura is being asked to sign is a document authorizing Sir Percival to borrow a portion of her 20,000 pounds, which is risky because if he fails to pay it back, it lessens the sum that will pass to her children someday. He suggests that in order to delay, she insist on having the document reviewed by her lawyer, which would be a reasonable step to take. As she dismisses the messenger, Fosco abruptly appears and offers to escort her back to the house. They arrive just as Sir Percival is returning, and he and Fosco have a private consultation. Afterwards, Fosco announces to Marian that the idea of obtaining Laura's signature has been set aside for the time being.
Overwhelmed, Marian collapses and is subject to a series of feverish dreams about Walter. She begs him to return, and he promises that he will, and that he will emerge unthreatened from various dangers. Marian awakens when Laura comes in to tell her that she has just encountered Anne Catherick. Laura had gone back to the boathouse searching for a brooch she had dropped the night before. While there, she was greeted by a young woman dressed in white, who returns her brooch. The woman mentions having known Laura's mother and identifies herself as Anne Catherick. She knows of Laura's marriage and explains that she had been lurking in the woods the night before, trying to find an opportunity to speak with her. Anne expresses her regret that she was unable to prevent Laura's marriage, explaining that she had previously been afraid of Percival. Now, she knows that she is dying so she is no longer afraid of him, and suggests that she is considering revealing his secret to Laura. Anne seems to think that if Laura knows her husband's secret, she will have more power in the marriage.
Anne explains that her mother has long known Sir Percival's secret, and shared it with her. Percival found out that Anne knew his secret, and she implies that she suffered as a result. Laura tries to get Anne to tell her the secret, but she becomes afraid that they are being watched and flees, asking Laura to return alone the following day. Laura went straight back to the house without seeing anyone else. Marian tells Laura to keep her meeting with Anne the next day; she will secretly hide to witness their conversation. She also tells Laura that she believes that there is in fact some secret that Sir Percival is desperate to hide.
The next day, Laura goes out to the boat house, and Marian follows a short time later. Marian, however, is surprised to find no one at the boathouse, just two pairs of footprints indicating the presence of both a man and a woman. Anxious, she hurries back to the house where she learns from the house keeper that Laura returned upset and accompanied by Sir Percival, who fired her maid. Marian goes to Laura's room to hear what happened but a servant prevents her from entering the room, saying she has been forbidden by Sir Percival to let her in. Angrily, she goes and confronts him. Surprisingly, Eleanor Fosco also takes her side, and backed by Count Fosco, she is allowed to go in and see Laura.
Laura explains that when she arrived at the boathouse, no one was waiting for her. She eventually noticed that there was a letter hidden for her from Anne. The letter told her that Anne had been sighted by a tall, fat man who tried to chase. She was able to avoid him, but did not dare to come back to meet her a second time. Laura and Marian realize that Anne's suspicions were right and that Laura and Anne were watched by Count Fosco, who then reported back to Sir Percival. Laura had barely finished reading the letter at the boathouse when Percival appeared. He knew about her meeting with Anne, and he had also already read the letter, which he takes away from her. Percival then demanded to know what Anne had told her, and Laura repeated the conversation but Percival insisted that she was hiding something. In order to try and force information out of Laura, he fires her maid and forbids her from seeing Marian.
Marian and Laura are now desperate and afraid. Marian writes to both the lawyer and to Mr. Fairlie, and has the maid Fanny convey the letters when she leaves the house, since they can trust no one else. Marian is increasingly anxious about the role of Count Fosco and Eleanor as spies and informants for Sir Percival. Knowing that Fosco and Percival are going to discuss their plans in the library, she sneaks out, crawls across the rooftop and hides where she will be able to eavesdrop on their conversation. She is shocked to hear Fosco inform Percival that she has written the lawyer again, especially since she took such care to safeguard the secrecy of the letters. Fosco also confirms that both he and Percival are in debt, and in need of money. Since they have not been able to secure Laura's signature for the loan, they have extended their credit for three months. Percival explains that he has no hope of getting money, but that if Laura were to die childless, he would inherit her twenty thousand pounds.
Fosco seems interested in this possibility, although Percival warns him not to pursue it, especially since Fosco also stands to gain by Eleanor receiving her inheritance in the case of Laura's death. Fosco also attempts to pry into what secret Anne Catherick might know about Percival, but does not get any information. Percival does explain that his position is dangerous, since he is convinced Anne has shared the secret with Laura. He is also worried because he knows that Laura is in love with Walter. Because of Walter's encounters with Anne, he assumes that Walter and Laura both have access to the secret, and have sufficient motive to use it against him so that they can be together. Percival knows he can control Mrs. Catherick, but is desperate to find Anne, which Fosco promises to help him do. Percival notes the strong physical resemblance between Anne and Laura. Fosco promises that he will come up with a scheme that will resolve both the problem of safeguarding the secret, and solving their money troubles.
When the conversation ends, Marian sneaks back to her room undetected. However, the time outside in the rain has chilled her, and she falls into a fever. The narrative ends with an entry inserted by Count Fosco, revealing that after she fell ill, he read her diary, and now plans to use the information found within it as part of his plan.
Marian's dream vision introduces a supernatural element, which is somewhat surprising considering that Marian has thus far been presented as a very rational and logical character. The dream aligns her with the dream vision described by Anne Catherick in her letter to Laura, suggesting that while Marian can participate in the kind of masculine investigations of truth that are linked to uncovering facts, she also has access to a more feminine, intuitive, and perhaps even psychic knowledge. Alongside the information which is conveyed in the dream, it makes it clear that psychologically Marian feels incapable of protecting Laura, and wishes she had a male figure to help her. Considering how empowered she often seems to be, this expression of vulnerability offers a balance, perhaps serving to remind Victorian readers that Marian is not completely violating the expectations of her gendered identity.
Indeed this entire final section of Marian's narrative reveals a tension between her strength and fierce devotion, and the fact that she is still vulnerable to the bodily weakness often associated with women. She falls ill twice, and the second time this illness is particularly disastrous since it leaves her incapacitated and allows Fosco to access and read her journal. As will later become clear, it is also Marian's illness that makes it possible for Fosco and Percival to enact their scheme. However, the illness comes after Marian performs a remarkable feat of climbing out of her window and crawling across the roof in order to be able to eavesdrop on the two men. Particularly for an upper-class woman who would be expected to be very controlled an modest in her physical activity, this is a daring and dangerous move. Marian explicitly comments on how she has to change her clothes in order to be able to do so, because the garments she would usually wear physically constrict her and make this kind of task impossible.
The eavesdropping scene is necessitated by the explicit introduction of some sort of secret which haunts Sir Percival. While Anne has up until this point seemed incredibly vulnerable due to her poverty, gender, and possible mental instability, it becomes clear in this section that she does have a kind of power. Sir Percival is actually afraid of her and what might happen if the secret got out, and while this endangers her, it also gives her a new agency. Now that Anne believes her death is imminent, she is also no longer afraid of being killed or returned to the asylum, so she poses a greater danger to Percival.
Percival's fear and the way in which he is at the mercy of female characters is also apparent when he learns that his wife has spoken with Anne, and becomes convinced that Laura must now also know his secret. On one hand, this false belief puts Laura in greater danger as he begins to isolate her, but it also makes her an actual threat rather than a passive object of abuse. With this sense of threat looming over him, as well as the ongoing financial troubles, Percival becomes more and more desperate.
The conversation between Fosco and Percival is thus extremely dark and foreboding, in that it raises the very real threat that they might conspire to kill Laura in order to access her fortune and ensure she never reveals the secret. In a reversal of previous approaches, Fosco seems more open to this possibility, while Percival cannot bring himself to condone outright murder. This contrast suggests the fundamental divide between the two: Fosco is more dangerous because his appearance is more deceptive, and he is the more truly ruthless of the two. Percival is also particularly troubled by what role Walter might play in all of this. His opinion of women is sufficiently low that he cannot really believe Laura capable of much harm on her own, but he worries about what could be achieved if she is assisted by a man.