Sixteen-year-old Bri is barely able to concentrate on her ACT practice test: she's waiting for a call from DJ Hype, telling her she can participate in a rap battle in the Ring later. Bri doesn't receive the call until nearly an hour later. At home, she finds her mom, Jay, serving "Popkenchurch," a conglomerate fast-food meal that means something bad happened. Jay won't tell her what. Bri's Aunt Pooh, a member of the Garden Disciples gang, takes Bri to the Ring. They skip the line and the bouncers refer to Bri as “Li'l Law”—a reference to her dad, the famous rapper Lawless, who was murdered by the Crowns gang twelve years ago. Bri thinks that she'd like to make her own name. When it's Bri's turn to rap, she goes up against a kid named Milez. He's the son of Supreme, Lawless's old manager. Milez insults Lawless, but Bri performs so well in the second and third rounds that she wins.
That night, Bri has her recurring nightmare: Jay is addicted to crack and is leaving Bri and Bri's brother, Trey, with Grandma and Granddaddy. This is a memory, and it's why Bri calls her mom “Jay” instead of “Mom.” In the morning, Bri feels excited: kids on the bus saw her rap battle video and her best friends, Sonny and Malik, congratulate her. As Bri tries to go through security, the guards, Long and Tate, ask to search her backpack. Bri refuses—she has illicit candy to sell, as she's saving up to buy a pair of Timbs—and Long slams her to the ground. Bri discovers in the office that Jay lost her job at their church, and the principal, Dr. Rhodes, insists that Long and Tate’s attack wasn't racially motivated. She suspends Bri for selling candy. When Bri and Jay get home, Bri angrily walks off to find Pooh. Pooh and her best friend, Scrap, comfort Bri, and Pooh shares that Bri has an opportunity to record a song. Trey, dressed for work at the local pizza place, drives up and forces Bri to come with him. He tells Bri that everything is going to be okay.
Bri doesn't tell Jay that she's going to record a song. At the studio, just as Bri is ready to start, Pooh is called away to a drug deal. Feeling alone and angry, Bri writes a song about the issues that black people face and the stereotypes that they're expected to play into. Bri isn't quite sure what to do with the finished product. At church the next day, Bri agrees to sit with Grandma and Granddaddy. Sister Daniels, the grandmother of Bri's annoying classmate Curtis, tells Grandma about what happened to Bri. She also insinuates that Jay is on drugs. During the meal later, Bri is shocked when Curtis sensitively says that he hates the way the black students are treated at school.
On the bus on Wednesday, Bri asks Sonny (who is gay) if Curtis is cute, and lets him listen to her song. He loves it, as do the rest of the passengers on the bus. At school, Sonny confides in Bri that he's been talking online to a guy named Rapid, but he's anxious about pursuing a relationship. Bri reassures him and accepts Malik's invitation to get pizza for lunch, hoping that it's a date. Bri is shocked to discover that it's not a date—Malik brings along Shana, who acts like his girlfriend. He embarrasses Bri, doesn't like her song, and asks Bri for permission to publicize the video he took of the incident with Long and Tate. Bri refuses.
That weekend, Jay makes Bri come to a food giveaway with her. As Bri finds a pair of Timbs in her size on a table, Supreme—who's volunteering at the event—compliments Bri. Bri isn't sure she can trust him, but when he mentions that he got local star Dee-Nice a record deal, Bri asks him to listen to her song. He loves it and asks for the link. Jay interrupts, but Bri feels hopeful—a record deal would lift her family out of poverty. On Christmas, Jay gives Bri Lawless's old chain. When Pooh stops by, she brushes off Bri's anger that she left Bri to record alone, and then takes offense to what Bri says in her song. She tells Bri to delete it, but Bri sends the link to Supreme instead. On the first day back to school after the break, Bri wakes up to the landlady asking for two months' rent. Jay, however, tells Bri that they can't sell Lawless’s chain. At school, Curtis tells her that her song is going viral, while Malik continues to express his dislike for the song.
Two weeks later, Bri has another battle at the Ring. As they prepare to enter, a Crown sees the chain, threatens Bri, and he and Pooh draw guns. The bouncers won't let Bri in, so Bri angrily leads the people in line in an angry, impromptu performance. Bri refuses to go home with Pooh and instead accepts a ride from Supreme. Supreme tells Bri that her behavior will make her money—it's scary for white parents and therefore, attractive to white teens. He tells Bri she needs a better manager. The next morning, Bri realizes that Supreme was right when she sees comments about her on the internet, but she feels she can't fire Pooh—especially because Pooh is bringing food over later. Trey saw the video of Bri's behavior and cautions her that she shouldn't act like that. He admits that her song is good, but points out that she has no idea what she's talking about in terms of guns and gang activity.
At school, Long and Tate are back. Students start to recite Bri's song and several boys, including Curtis, attack Long and Tate. Bri grabs Curtis and runs with Malik, Sonny, and Shana to Malik's house. There, Malik tries again to convince Bri to let him publicize the video of her being attacked, but she refuses. At home, Jay finds out about Bri's song when the school rally ends up on the news. She forbids Bri from rapping. This makes Bri so angry that she agrees to meet with Supreme the instant he texts her.
Supreme buys Bri breakfast and gives her a gift—brand new Timbs—in congratulations for her song going viral. Dee-Nice is there too, and Bri realizes that Supreme is luring her away from Pooh. When Dee-Nice tells Bri that he can care for his family thanks to Supreme, Bri agrees to work with Supreme. When Bri gets home, Jay makes Bri study for the ACT. When Bri gets her phone back, she sees that a white reporter started a petition to get her song removed from its online platform. Enraged, Bri goes live on Instagram and blasts the censorship attempt. She regrets it in the morning, especially when Trey tells her he's seen it. Sonny and Malik arrive to speak to Bri. Bri is angry with them and tries to ignore them, but finally agrees to play video games at Malik's house. Malik convinces Bri to let him use the footage of her attack to make a music video for her song. Once Sonny leaves, Malik hugs Bri and kisses her. The kiss is awful, and they walk home awkwardly.
Halfway to Bri's house, the Crown drives by, punches Malik, holds Bri at gunpoint, and steals Lawless’s chain. Bri calls Pooh and tells her what happened. Pooh takes Bri home and disappears. In the morning, Bri wishes she'd sold the chain—the electricity in her house has been shut off. The next evening, Grandma and Granddaddy stop by. When they learn that the power is off, Grandma accuses Jay of being a bad parent, but Jay insists that she's just poor. Granddaddy gives Jay money for the bill. When they leave, Trey sends Bri outside. She gets a call from Supreme, telling her she has an interview with DJ Hype over the weekend.
Four days later, Bri accompanies Jay to the PTA meeting with the superintendent about the issue of school security. Though both Shana and Jay speak out about racial profiling, Dr. Cook refuses to acknowledge the issues. He begins to change his tune when Jay corners him afterwards, makes him understand that Bri is a child, and asks him to protect her. He also accepts Jay's resume, as he's looking for a receptionist. About a week later, Bri hears from Pooh. Near Pooh's apartment, small kids stop Bri for autographs and recite her lyrics. Hearing her words from children chills Bri, especially when the oldest, Jojo, asks Bri if she shoots gangsters. Pooh didn't get the chain back or kill the Crown, and she's surprisingly okay that Bri hired Supreme. She makes Bri promise to get out of Garden Heights—just as SWAT vans arrive and begin a drug raid. Curtis drags Bri into Sister Daniels's apartment while Pooh gets arrested. Curtis comforts Bri, they kiss, and he drives her home later. When Bri tells Jay that Pooh was arrested, Jay cries and locks herself in her room.
Bri is emotional on the day of her interview. Supreme laughs when Bri asks him to use her name and warns her that DJ Hype will try to push her buttons. True to form, Hype asks Bri about whether her song incites violence and is sexist. Bri angrily refuses to continue the interview. Supreme praises her: she acted like a "ratchet hood rat" and it will help her image. Bri is horrified. She goes immediately to see Trey at work. Trey is livid until Bri says she just wanted to save the family, at which point he tells her that she's a gift and she saved him. A few days later, Bri goes into Jay's room to ask her to get up. Jay invites her to come see Pooh in jail the next day, and Supreme calls to ask Bri to record a song for a record executive after school. On the bus, Curtis asks Bri out in front of Sonny and Malik. At school, Shana is disappointed that Bri can't come to a meeting with Dr. Cook after school, but offers Bri her support.
After school, Supreme takes Bri to the studio. The white executive, James, speaks about Lawless as though he made stupid decisions and as though Bri isn't there. He calls her sassy, which Bri hates, and when Dee-Nice arrives, they tell her that he wrote a song for her. Bri tries to refuse, but ends up recording it even though it's violent and sexist. At the jail the next day, Pooh spills all of Bri's secrets to Jay. Jay is livid and refuses to bail Pooh out of jail, since Pooh is still plotting revenge on the Crown who stole the chain. Outside, Jay tells Bri that she can't rap until she figures out who she is.
A few days later, Bri accompanies Sonny and Malik to the park to meet Rapid. Bri and Malik make up, Rapid turns out to be Miles, and Miles tells Bri that Supreme makes him pretend to be straight and he's giving up his rap career for this reason. Bri thinks about this information at church the next day. Trey's new girlfriend Kayla comes with him, and Bri realizes she's okay with Curtis being affectionate in public. Bri panics, however, when Jay, Grandma, and Granddaddy announce a family dinner after church, especially since Grandma isn't being nasty to Jay. At their house later, Jay apologizes for leaving Bri, and Bri starts to call her "Mom.” Jay tells Bri and Trey that they're moving in with Grandma and Granddaddy so that Trey can go to grad school. Trey convinces Jay to let Bri rap, as long as she fires Supreme.
At the Ring the next week, Bri acts as though she's still on good terms with Supreme. She's terrified when she sees Crowns there, taunting her with the chain, but she insists on freestyling instead of performing Dee-Nice’s song. Supreme and James walk out. Only a few weeks later, Bri gets an invitation on Twitter to collaborate on a song with a famous rapper.