As Finch stands at the top of his high school’s belltower, prepared to jump, he wonders if today is a good day to die. Finch has spent the past few months “asleep” (his term for a depressive episode), but now that he’s “awake,” he’s fixated on death. However, he realizes he’s not alone: a popular girl, Violet Markey, is on the other side of the tower. He talks Violet off the ledge, and she convinces him not to jump either. Knowing that there are onlookers below, Finch makes it seem like Violet came up to save him, not to contemplate killing herself. They both make it down safely.
Later that day in U.S. Geography, their teacher, Mr. Black, announces a project to “wander Indiana.” Finch tells the class that he’s going to work with Violet. Violet feels awful for almost killing herself. She knows that her death would devastate her parents—especially since Violet’s older sister Eleanor died in a car crash last spring. Since her death, Violet hasn’t been able to write—something she once enjoyed—and now she wears Eleanor’s glasses to try to connect with her sister. She hasn’t been in a car since Eleanor died and insists on biking everywhere.
Wanting to appear normal to Violet, Finch creates a Facebook account so he and Violet can communicate with each other. They come up with their “Rules for Wandering” and begin to exchange Virginia Woolf quotes. Though Finch is familiar with Virginia Woolf’s suicide note, he hasn’t read the rest of her work. After school one day, Finch and Violet bike to Hoosier Hill (the highest point in Indiana) for their school project. Finch insists that it’s beautiful, but Violet is underwhelmed. Next, Violet insists they go visit the Bookmobile Park. Though she gives Finch directions to get there by bike, Finch insists they take Finch’s mom’s car, a Saturn that he calls Little Bastard. Violet relents. As they continue to visit sites across Indiana, their chemistry grows—and Finch encourages Violet to start writing again so she can document their project.
As their relationship progresses, Violet starts to heal and improve. She realizes that she doesn’t enjoy spending time with her former friend Amanda and Amanda’s boyfriend Roamer. Instead, Violet starts sitting with Finch’s friend Brenda and some other girls. She comes up with the idea for a new web magazine to replace the website that she and Eleanor ran, and she decides to stop wearing Eleanor’s glasses.
Finch’s mental health, meanwhile, starts to decline; he constantly thinks about suicide and researches various methods of killing himself. He attends mandated Sunday night dinners with his sisters, Kate and Decca, at Finch’s dad’s house, but he doesn’t enjoy them—his dad is physically and emotionally abusive, and Finch suspects that his dad fathered a son with his new wife, Rosemarie, while he was cheating on Finch’s mom. Finch is, at times, unable to read or write, and he experiences headaches during which he can “feel sound” and “hear space.” He knows he could talk to his mom—but his mom would only tell him to take painkillers and remind him that he’s sensitive. His counseling sessions with Mr. Embry don’t help much, since Finch does everything in his power to keep Mr. Embry from discovering how poorly he feels. Finch goes on runs to try to clear his head, but it only works sometimes. He also repaints his room blue when it starts to feel claustrophobic.
On the first warm day of the year, Finch takes Violet to the Blue Hole, a lake that’s supposedly bottomless. Finch dives down as deep as he can, enjoying the weight of the water—but he doesn’t want to upset Violet, so he returns to the surface. She’s enraged that he was underwater for so long; she thought he’d died. Finch encourages her to scream and let go of her anger. When they get back to Finch’s house later, they have sex for the first time. Then, they go to the Purina tower to talk, but they end up falling asleep and spending the night there. Violet’s mom and Violet’s dad are enraged in the morning, and they forbid Violet from seeing Finch anymore.
Both Violet and Finch are distraught. Violet is angry enough to want to run away with Finch, while Finch’s mental health continues to decline. He starts to spend all of his time at home in his closet, though he continues to attend school sporadically. When Finch goes back to school after spring break, he continues to have issues reading. Then, in a meeting with Mr. Embry, Mr. Embry asks Finch what he knows about bipolar disorder. Finch stops listening and tries to just look pleasant—in his mind, “crazy people” have bipolar disorder, and it’s a way to explain people away. Later that day, when Roamer insults Finch in the hallway, Finch chokes Roamer and is expelled from school. He calls Violet and invites her to skip class and see another Indiana wonder with him, but Violet refuses. She’s concerned—Finch sounds unwell.
Finch spends most of the following day in his closet. At one point, he checks the landline’s voicemail and deletes a message from Mr. Embry to Finch’s mom. After dinner, he takes a large dose of sleeping pills but runs to the hospital and asks them to pump his stomach. When he comes to after the treatment, he leaves the hospital without telling them who he is. Not long after, Finch decides to attend a Life Is Life meeting, a support group for teenagers who have thought about or attempted suicide. He’s shocked to find that Amanda also attends the group; she struggles with an eating disorder and has attempted suicide twice. The meeting is depressing: the other kids seem altered by the medications they take, and it seems like their identities are tied to their mental health diagnoses.
Violet borrows her parents’ car to visit Finch because she’s concerned about him, and she joins him in his closet. Finch tells her about a cardinal that died when it hit the living room windows too many times. He was just a kid at the time, and he experienced his first “black mood” after the cardinal died. Violet is disturbed—and she’s even more disturbed when Amanda pulls her aside the next day and says that she saw Finch at a suicide support group. Violet visits Finch a few days later to celebrate his birthday. At first, it doesn’t seem like there’s anything amiss with him—aside from the fact that he’s still living in his closet. But when Violet mentions what Amanda said and asks Finch to get help, Finch coldly tells Violet to leave. Back at her house, Violet asks her parents to help her help Finch. She’s concerned for his safety. But Finch’s mom, Kate, and Decca all refuse help. And when Finch disappears, they’re unconcerned since he always comes back.
A few days after he leaves, Finch starts sending Violet cryptic texts and never responds when she asks him questions. Finch’s friends and family aren’t concerned at all. Meanwhile, Violet and her parents celebrate the anniversary of Eleanor’s death, and Violet continues to work on her new web magazine. Then, one Sunday late in April, Kate shows up at Violet’s house with an odd email from Finch—and the concerning news that Finch has stopped checking in. Violet discovers that she and Finch’s friends have all received cryptic emails as well, so she goes to Finch’s house and inspects his closet again. She finds two lines of text and thinks she knows what they mean. She drives to the Blue Hole, where she finds Finch’s clothes neatly folded. After she calls 911, emergency responders retrieve Finch’s dead body from the water.
Violet’s parents insist on going with her to Finch’s funeral. The preacher doesn’t mention suicide once—this is in part because the authorities couldn’t rule Finch’s death a suicide, since he didn’t leave a note. As the days and weeks pass, Violet grows increasingly angry. Kids who once bullied Finch now seem to idolize and miss him. Violet has a counseling session with Mr. Embry in which Mr. Embry encourages her to realize that Finch’s death wasn’t her fault—instead, she needs to think of herself as a survivor and learn to live despite this loss. Violet also starts to reconnect with Amanda.
When Violet found Finch’s body, she also found and took the map that she and Finch used for their geography project. She discovers that he marked five more sites for her to visit, so she visits them in order. At each place, Finch left her something important to see or do. She finds a pair of his shoes on “shoe trees” near the Kentucky border, and she paints a coat of paint the color of Finch’s eyes on the world’s biggest ball of paint (Finch painted it violet in honor of her). She visits an abandoned drive-in theater, where Finch wrote “I was here” on the screen. The fourth site is a monastery and grotto, and the final site is a small roadside chapel. The chapel was built to honor the victims of car crashes, a nod to Eleanor. Violet sits in a pew and cries as she reads lyrics and music that Finch left for her in the Bible—the song talks about how happy and whole she made him feel.
Several months later, Violet swims at the Blue Hole and remembers Finch. She misses him and still sees him everywhere, but she also thinks of all the places she has yet to see.