In Chapter 3, the narrator squirms in secondhand awkwardness while Mrs. Van Hopper makes a fool of herself in front of Maxim. By the end of the scene, Maxim uses verbal irony and dramatic irony to establish rapport with the narrator at Mrs. Van Hopper's expense:
He got up at once, pushing back his chair. “Don’t let me keep you,” he said. “Fashions change so quickly nowadays they may even have altered by the time you get upstairs.”
The sting did not touch her, she accepted it as a pleasantry.
After droning on at length about subjects the narrator cannot believe Maxim would want to hear, Mrs. Van Hopper has been summoned for a dress fitting. Maxim uses polite-sounding language as he excuses her. He makes it sound as though he recognizes the importance of the dress fitting and respects Mrs. Van Hopper enough not to keep her from urgent matters. Under the mask of politeness, though, there is another interpretation. The "sting," as the narrator calls it, is the idea that Mrs. Van Hopper doesn't seem to do anything quickly. Her long-winded ramblings have wasted everyone's time, and at this rate she is never going to make it upstairs before the fashion cycle turns over.
Maxim's verbal irony is also an attempt to create dramatic irony. Mrs. Van Hopper does not notice the insult hidden behind politeness, but the narrator does. Maxim later sends the narrator a note apologizing for his rudeness. While he may say he is sorry, he is also making clear that he meant for her to catch the fact that he was making fun of Mrs. Van Hopper. More even than making light of the older woman's clueless nature, Maxim wants the narrator to be in on the joke with him. The dramatic irony draws the narrator to Maxim by appealing to her sense of self-importance.
In Chapter 8, the narrator wakes up on her first morning at Manderley. Maxim leaves her largely to her own devices, and dramatic irony soon makes it clear that she is out of her element:
[O]ne of [the servants] laughed—Robert, I supposed. Perhaps they were laughing about me. I went upstairs again, to the privacy of my bedroom, but when I opened the door I found the housemaids in there doing the room; one was sweeping the floor, the other dusting the dressing table. They looked at me in surprise. I quickly went out again. It could not be right, then, for me to go to my room at that hour in the morning. It was not expected of me. It broke the household routine.
The narrator is brand new to the house and hardly knows her way around. She doesn't yet have a routine of her own, and yet she immediately realizes there is a "household routine" she does not know. It is hard to say the extent to which the servants are all laughing behind her back and the extent to which she might simply feel as though they are laughing at her. What is clear is that people in the house expect her to do certain things and be certain places at different times of the day. Because no one has given her a schedule or run through the unspoken rules with her, she is doomed to violate rules and norms in small ways that add up. Walking in on the housemaids may not be much of a transgression on its own, but it piles up on top of several others, such as expecting a fire in the library in the morning and tripping on a step she did not realize was at the threshold of the dining room. All of these small transgressions together make the narrator feel like an outsider to the house and to the social class into which she has married. This feeling puts her on the defensive and causes her to spiral into regret over her marriage—that is, until Maxim lets her and her alone in on the deepest secret of the house, Rebecca's murder. At that point, everything changes for the narrator because she now has access to power, in the form of information that others do not have.
One important instance of dramatic irony occurs in Chapter 16, when the narrator debuts the white dress she has commissioned for the costume party. Maxim's and others' reaction to the dress takes the narrator entirely by surprise and clues her and the reader in that she has missed some very important information:
“What the hell do you think you are doing?” [Maxim] asked. His eyes blazed in anger. His face was still ashen white.
I could not move, I went on standing there, my hand on the banister.
“It’s the picture,” I said, terrified at his eyes, at his voice. “It’s the picture, the one in the gallery.”
There was a long silence. We went on staring at each other. Nobody moved in the hall. I swallowed, my hand moved to my throat. “What is it?” I said. “What have I done?”
This moment is heavy with emotion. Maxim is so angry that his face has turned white and his eyes are "blazing." The narrator is frozen with shock and fear of her own husband, and the sense that she has committed an unforgivable social faux-pas. The reader can already guess at part of what has happened: somehow, the white dress and wig remind Maxim and everyone else of Rebecca.
The narrator has had no reason to suspect that her costume will have such an upsetting effect. In fact, she has been teasing Maxim, Frank, and others all week with hints about how much they will love her outfit. She is proud of matching the picture from the gallery and thinks she will finally show herself to be clever, poised, and mature enough for Maxim. She has enjoyed keeping the outfit a secret and has looked forward to making the perfect, breathtaking entrance at the party.
This scene completely reverses the dramatic irony of the narrator's secret. Instead of playing the upper hand, she finds out once again that she does not even know the rules of the game at Manderley. She is an outsider who will never know all the lore of this place. The gaps in her knowledge doom her to missteps such as this when she least expects them.
As the narrator hurries away from the party, she realizes that Mrs. Danvers has in fact manipulated her status as an outsider to trick her into wearing the same outfit Rebecca wore to the last costume party at Manderley. This important scene underscores the fact that in the aristocratic world the narrator has joined, information is power. Not knowing everything that happened when Rebecca was alive puts the new Mrs. de Winter in a dangerous position because she does not know what traumatic memories she may unknowingly stumble into—or, as in this instance, what traumatic memories she may be coaxed into.
It is worth noting that as she is writing years later, the narrator keeps the reader in the same suspense she was in when she lived at Manderley. The narrator does not necessarily want to control the reader, but she does use dramatic irony to convey the emotional memory of what it was like to live in Rebecca's shadow.
In Chapter 19, everyone is startled when a steamer runs aground in the harbor. The narrator makes small talk about it with Ben, and a poignant moment of dramatic irony ensues:
“She’ll break up bit by bit,” he said, “she’ll not sink like a stone like the little ’un.” He chuckled to himself, picking his nose. I did not say anything. “The fishes have eaten her up by now, haven’t they?” he said.
“Who?” I said.
He jerked his thumb towards the sea. “Her,” he said, “the other one.”
“Fishes don’t eat steamers, Ben,” I said.
“Eh?” he said. He stared at me, foolish and blank once more.
The narrator is confused about Ben's meaning and assumes he is not making sense to her because he is developmentally disabled. She tries to gently correct him, telling him that fish don't eat boats. Ben looks confused in return, but the narrator again attributes their miscommunication to his disability.
In retrospect, it is clear to the narrator and the reader that Ben is actually revealing a majorly important detail about Rebecca's death. His use of the pronouns "she," "her," and "one" make his statement ambiguous. It is common to refer to boats with female pronouns, and that is just what Ben does when he claims that "She'll [the steamer will] break up bit by bit." The steamer, he remarks, will not sink to the bottom of the harbor "like the little 'un." The narrator isn't sure how to respond because she does not know what he means by "the little 'un." In retrospect, knowing how the story turns out, it is clear that Ben means that the big steamer won't sink like Rebecca's little boat.
The next mix-up happens after Ben pauses and laughs. He says that the fish have probably eaten "her" up by now. The narrator doesn't realize that the antecedent of "her" is no longer a boat, but Rebecca herself. When she asks for clarification, Ben says, "the other one," meaning Maxim's other wife. At this point, the narrator gives up trying to follow him. Looking back, it is clear that Ben is completely lucid.
Ben is the only eyewitness to the murder aside from Maxim himself. He does not even seem very careful to keep the murder a secret. This scene demonstrates that sometimes, secrets hide easily in plain sight because people believe what they want to about the people around them.