Aza struggles to drive Mom's car to Applebee's. She keeps thinking about the accident and thinks that the worst part of the accident was losing her dad's phone. She gets to Applebee's and hugs Davis. Aza thinks that Davis is going to want to "put his bacteria in her mouth." She remembers Dr. Singh saying that unwanted thoughts are like cars on the road and you don't have to get in them. Aza gets into the mental car.
Again, even though Aza appears to be "better" by many standards (and one could even call her courageous here for driving after the accident), she's not 100% well. Her anxiety still has power over her life, and even if Davis himself is fine, the bacterial fear that he represents is not.
Davis and Aza make small talk as Aza's mind begins to spiral about the dangers of kissing Davis. Davis brings Aza out of her reverie, and she asks him to sit on the other side of the booth. She says she's generally good, but not good right now, and that she can't do a relationship. She says she probably won't get any better than she already is. Davis insists that he's fine doing things the way they are, but Aza says that he certainly wants to kiss and "do other normal couple things." She tries to explain that kissing is one of the things her brain believes is going to kill her, and she knows she's hurting Davis.
Language begins to fail Aza here. Although she's trying to explain the intricacies of her brain to Davis, and is also trying to talk herself down and away from her anxiety, neither is working. As the two characters essentially break up their unofficial relationship, Aza sees once again that Davis can't have everything he wants just because he has money. Money can't solve Aza's mental health problems and make her feel okay with physical intimacy .
Davis asks Aza if she feels like she's getting better. Aza thinks that everyone wants to hear that she's getting better. She says that she feels fragile and asks how he and Noah are. Davis says that Noah is still struggling. One minute he's a kid who cries, and the next he's a vodka-drinking "dudebro." Davis begins to seem uncomfortable, and it occurs to Aza that Davis probably likes that she doesn't ask many questions.
Aza again acknowledges that the narrative of illness isn't always appropriate for the realities of mental illness. Noah is still acting out and experimenting with his identity. Drinking vodka is an activity that is supposed to be for adults, while crying in bed isn't. In that sense, he's experiencing a kind of split identity, much like Aza—suggesting that perhaps such splits are just part of growing up.
The conversation struggles. Aza realizes that they're never going to be what they were. She texts Davis when she gets home. He texts back that he feels like Aza only likes him at a distance when she can't be close. She never replies.
Davis suggests that the closeness Aza felt when the two were texting and facetiming wasn't shared. Her control and power was his powerlessness—as he wanted to be closer to her than she would allow.
At lunch the next day, Daisy grabs Aza and asks if she wants to go to a guerilla art show. She explains that Mychal submitted his photography project to an arts collective and it was accepted into a show that will take place in part of the Pogue's Run tunnel, one of the tunnels that Pickett Engineering was supposed to expand. Daisy says she'd really appreciate it if Aza came. Aza finally agrees and tells Daisy she loves her.
Aza finally uses her words to actually tell Daisy how she feels about her—something that she hasn’t done much in the past. In doing so, she strengthens her relationship with Daisy. The show in the Pogue's Run tunnel brings the story back to the beginning by bringing it back to Pickett Engineering, the company at the center of the mystery of Pickett Sr.’s disappearance.
When Daisy and Mychal stop to pick up Aza that night, Aza feels underdressed. In Mychal's minivan, Daisy and Aza sing along with one of their favorite songs. Aza sings the background vocals that repeat "you're everything," and thinks that it's true. She thinks that a person can be the narrator, the protagonist, and the sidekick. When the song changes, Aza thinks about turtles all the way down. She thinks that the old lady and the scientist were both right. The world is billions of years old, but it's also the stories that people tell about it.
Aza is beginning to integrate her different selves. She's certainly the protagonist of the novel, even though she often positioned herself as Daisy's sidekick through her narration. Finally, Aza seems to realize that her words do indeed have power. She can be all these things and tell stories about herself and the world, and what she tells will influence how she and others think about herself and the world.
Mychal parks in a business parking lot. He, Daisy, and Aza get out into a crowd of twenty-somethings and middle-aged couples. A woman approaches Mychal. He tells her he has a piece in the show, and she introduces herself as the curator. She begins to lead them down to the gallery, but stops every few seconds to introduce Mychal to someone. Finally, Daisy tells Mychal that she and Aza are going to head down to the gallery.
Mychal actually gets to try on the identity of a successful artist at the show. Compare this to Mychal's earlier experience in Davis’s house: this experience is far grungier and messier than Davis’s manicured home, which suggests that being an artist may not be as easy or as clean as Mychal thought it might be.
Daisy and Aza make their way down a hill, guided by a waving flashlight beam ahead. A man at the opening of the tunnel gives the girls hard hats with lights and tells them how to get to the gallery. The tunnel smells of sewage and rot, and they can hear rodents scurrying around. Daisy is scared, but Aza isn't. She follows the headlamps ahead of them and leads Daisy to the gallery, which is lit only by the viewers' headlamps. Mychal's piece is Aza's favorite. Someone sets up a stereo and begins passing around cups of wine. Aza feels sweaty and asks Daisy if they could go for a walk.
Aza shows that she's becoming more aware of her reactions to intense situations (like the darkness in the tunnel), and she's far more willing to use her words to express her needs and involve others than she once was: she asks Daisy to accompany her when she gets nervous, presumably about the prospect of drinking anything inside the sewage tunnel.
Daisy isn't thrilled, but agrees to go with Aza. Daisy says that she doesn't understand how Aza can be so calm in a nasty sewer, but has panic attacks about her potentially infected finger. Aza insists that the sewer isn't scary and tells Daisy to turn off her headlamp. When Daisy finally agrees, Aza explains that her mind feels like this in the dark. She doesn't know where the walls are or which way is up. She doesn't have control over decisions or fears, but says that being able to turn the light on is power. Daisy asks if it's that bad, and asks if Aza's flashlight is working now.
This metaphor allows Aza to communicate to Daisy what inhabiting her mind is truly like: limitless, but scary because it's limitless. When Aza says that there's power in being able to turn on the light, she's saying there's power in knowledge and control. This thematically ties back to Aza's medication, as the medication can be seen as a way for her to turn on the light. It allows her some control over her dark and worrying anxiety.
As they walk, Daisy asks if Aza would mind if she killed off Ayala. Aza says that she read the most recent story and is actually coming to like Ayala. Daisy promises Ayala a heroic death, and comments that the smell is getting worse. She wants to go back, but Aza sees a pinprick of light and wants to find it. The end of the tunnel is where the water from the city is supposed to be diverted from the White River, but the water is dripping in the river anyway.
Here, the girls are confident enough in their safety and in their control of the situation that they persist in following the tunnel, despite the shockingly bad smell. When Daisy offers to kill Ayala, she offers to give Aza a way to simplify her identity by just getting rid of a problematic part of it.
Aza admires the view of the city from the mouth of the tunnel. Daisy sits down and she and Aza talk about college and life. Daisy wonders if anyone will ever finish the tunnel. Aza says she hopes they don't so they can come back and admire the view. Suddenly, Aza asks where Pogue's Run starts and where its mouth is. Daisy realizes that they're in the mouth of the Pogue's Run tunnel: they're in the jogger's mouth. Aza stands up and feels as though Mr. Pickett is behind them.
It turns out that the phrase “jogger’s mouth” was a kind of linguistic riddle or code word for the mouth of the Pogue’s Run tunnel—and the key to the riddle is the similarity between the words “Run” and “jog.” Notably, this light bulb moment doesn't come with celebration and fanfare, only fear.
Daisy asks what they do as they start walking back to the gallery. Aza says that she'll tell Davis, but otherwise they do nothing. Daisy wonders if Mr. Pickett is in the tunnel and comments again on the smell.
The smell suggests that Mr. Pickett might be dead in the tunnel—and furthermore that when Mr. Pickett tried to take control of his life, he failed miserably and lost his life in doing so.
In the gallery, Aza thinks that solving mysteries should bring closure, but they really just raise more questions. When she and Daisy find Mychal, they pull him away from the women he's talking to and head out of the tunnel. When Mychal asks how their evening was, Daisy deflects and asks him to talk about his evening.
Aza and Daisy learn that solving mysteries can happen in the same way that Malik described science for Aza. It leads to more questions, not answers that make things better immediately.
When Aza gets home, Mom asks her what the smell is. Aza explains that it's a mix of things, and Mom tells Aza to sit down and talk to her about what she was doing. Aza does. She tells Mom everything about the mystery and the jogger's mouth, and that she's going to tell Davis but not the police. She explains that if she tells the police, Tua will get the Pickett house and the money. Mom mumbles about "the madness of wealth" and that if you worship money, it will spend you. Aza says that they need to be careful what they worship, and Mom lets Aza go shower. Aza wonders what she'll worship when she gets older. She realizes she's at the beginning of life and can be anybody.
By finally allowing Mom to know what's going on in Aza's life and in her head, Aza continues to loosen her spiral. She and Mom can now talk and try to make sense of Aza's discovery together. This moment marks Aza's moment of true discovery. She finally realizes that life will indeed go on, and she has many years ahead of her. Notably, she realizes that she controls what happens during those years, which represents her taking Dr. Singh's words to heart.