The film opens with the Carter family seated at the kitchen table. Patriarch Maverick (Russell Hornsby) gives his three children instructions on what to do in the event that he or they are ever pulled over by police, but to also not be ashamed of their identities as black children. Maverick then hands them Black Panther ten step programs.
Present Day in the early 2010s
Starr (Amandla Stenberg) is Maverick's daughter who lives with him, her mother Lisa (Regina Hall), her older half-brother Seven (Lamar Johnson) and younger brother Sekani (TJ Wright). Maverick was once part of the most violent gang in the neighborhood, the King Lords, but he has since left that life behind. The Carters live in the mostly poor, predominantly black neighborhood of Garden Heights. While gang violence is prevalent, there are places like Maverick's grocery store and other shops that thrive.
Starr attends Williamson, a prep school in a rich, mostly white area. Starr feels that she can't be "too ghetto" with her Williamson friends, but not "too preppy" around her Garden Heights friends. She is dating Chris (KJ Apa), who just recently tried to have sex with Starr when she wasn't ready. He comes to her at school to apologize and show off his corny dance moves. Starr acknowledges that she and Chris get looks from the white girls who are too scared to say anything due to their interracial relationship.
Starr attends a party in Garden Heights with Seven's sister Kenya (Dominique Fishback), whom Starr sometimes can't stand. Kenya notices a girl outside who's been talking trash about her, so she expects Starr to back her up in a fight, but Starr refuses to get involved. Starr strays from Kenya and meets up with her childhood best friend Khalil (Algee Smith). The two chat for a while until they witness an altercation between a group of guys, followed by the sounds of gunshots. Everybody runs out of the house, and Starr gets into Khalil's car.
Khalil drives Starr home as the two listen to a Tupac song. Khalil points out a famous saying of the late rapper - "The hate u give little infants fucks everybody" (which becomes an acronym for THUG LIFE). The two pull over and start to reminisce about their childhood with another friend named Natasha who is no longer with them. They talk about playing with "Harry Potter" wands and how Khalil was Starr's first kiss. He kisses her in the car, but she tells him she has a boyfriend. Khalil pulls out to drive again. But a short while later, they are pulled over by the police. The cop, Officer Mackintosh, AKA 115 (Drew Starkey) (nicknamed due to his badge number) exits his squad car. He tells Khalil he pulled him over for failing to signal a lane change and asks for his license and registration, but Khalil argues over the matter even as Starr, who has her hands on the dashboard, tells him to comply. 115 orders Khalil to step out of the vehicle as he runs his license. Khalil looks into his car to see if Starr is okay, but she keeps telling him to do what the officer says. Then for some reason, Khalil reaches into his car to take out a hairbrush, and 115, mistaking it for a weapon, opens fire on Khalil. Starr runs out of the car to Khalil's side, but 115 cuffs her. He quickly realizes Khalil didn't have a weapon in his hand and he frantically calls for an ambulance. Starr weeps as Khalil slowly dies by her side.
Starr is brought in for questioning by two detectives with her mother by her side. They ask questions regarding Khalil potentially carrying drugs and not about the incident in question. Starr's uncle Carlos (Common), another officer, comes in and takes her and Lisa out of the room. Starr is left traumatized and haunted by the incident even days later, and she cannot bring herself to tell anyone at school about it.
Starr attends a wake at Khalil's home where she gives her condolences to his grandmother, Miss Rosalie (Rhonda Johnson Dents), who tells Starr that she was the only real friend Khalil ever had. She also confides to Starr that Khalil was selling drugs for King (Anthony Mackie), leader of the King Lords. After the wake, Maverick and Carlos argue over whether or not 115 will be investigated for killing Khalil.
The Carters attend Khalil's funeral at a church. Seven's biological mother Iesha (Karan Kendrick) loudly orders him to join her, King, and his siblings in the back over the sound of the choir. Seven doesn't want to go, but Lisa tells him to just do it. A lawyer, April Ofrah (Issa Rae), goes up to give a speech on how what happened to Khalil has happened to too many young unarmed black teens that are being killed by the police all over the country at an alarming rate. She also implies that she knows that Starr was the witness to Khalil's shooting, even though that information had not been disclosed to the public.
April visits the Carters that evening to offer Starr a chance to do an interview regarding the incident. She appears hesitant, and April says it's okay if she chooses not to. Before April leaves, Starr brings up what happened to Natasha. They were playing with Khalil as kids until a King Lord shot Natasha dead in the streets. Starr was afraid to snitch on him because she feared he or the other King Lords may retaliate. She later found out months afterwards that the shooter was killed in an unrelated rival gang hit, but she still didn't speak up, and she has felt guilty ever since. April tells her not to feel guilty and says that this is her chance to get justice for Khalil.
Starr's parents take her to the interview where her face is blurred out and her voice is distorted. She tells the interviewer that Khalil was working for the King Lords, which King sees on TV.
Later, as the Carters are having dinner, Starr and Maverick see King and his goons standing outside threateningly. Maverick goes outside to deal with King, who knows that Starr mentioned him in the interview. This leads to an altercation that is broken up just as the police arrive and two officers approach. Maverick calmly complies with the cops until one officer, a black man, presses Maverick against the window in front of his family. Lisa runs out to hand the cops his ID, but it gets more heated when the white cop presses Seven for his ID. Starr and another woman record the confrontation on their phone to show how the cops treat black folks, and the cops back off and leave the family alone. However, little Sekani is shaken up by it. When the family returns home, Starr tearfully apologizes for getting King to go after them. Maverick stands his kids outside the house and tells them to recite a step from the program he gave them earlier, which is to have something to live and die for, and for Maverick, that's his whole family.
The stress from the incident puts more of a strain on Starr's life at school. The other kids use Khalil's death as an excuse to get out of class to make it look like they care and are trying to protest. Starr grows more distant from Chris, and things go sour with her friends Hailey (Sabrina Carpenter) and Maya (Megan Lawless) when they watch a news report on how 115 and his family have been getting death threats for shooting Khalil, and Hailey shows more empathy for 115 than for Khalil. When Starr talks to her mom about this, Lisa tells her that she has always been following Hailey's word without thinking for herself.
On prom night, Starr attends with Chris, but all the other kids are looking at her weird. He takes her into his limo and says that he knows Starr was the witness to Khalil's death, and he is upset that she kept that from him. Starr feels that Chris doesn't grasp how the situation is for her as a black girl, and that he appears to ignore her identity as a black girl. Chris argues against that, saying that he sees her for who she really is.
After they reconcile, Chris takes Starr and Seven home so that he can meet Maverick. The meeting turns out poorly, because although Lisa is happy to meet Chris, Maverick is none too pleased to see that Starr is dating a white boy. After Chris leaves, Maverick tells Starr he feels he has failed to show her what a black man should be, and Starr says that he showed her what a man should, period. As the family embraces, gunshots fly through the house, sent by King's goons. Maverick brings the family to Carlos's house to stay for safety, but he and Seven go back to stand guard at the house in case King comes back, despite Lisa's protests for neither of them to go back.
Starr later goes before a grand jury to give her testimony against 115, and to tell everyone of the type of person that Khalil really was.
At school, Hailey confronts Starr and asks her when she will get over Khalil's death. Starr has had enough, and she counters that Hailey is only ever friendly with her because she views Starr as a non-threatening black girl, which Hailey confirms. She also tells Starr that due to Khalil's history as a drug dealer, he would have probably gotten killed anyway, and that it made sense for the officer to mistake his hairbrush as a weapon. Starr then grabs Hailey's hairbrush from her backpack and starts yelling at her while holding the brush like a weapon, which drives Hailey to tears. Starr tells her that she now knows what it feels like for black folks.
Chris drives Starr home, but they start to see a group of black folks protesting toward City Hall. Starr and Chris look at their phones and learn that 115 was not indicted for Khalil's death. Starr then gets a text from Kenya to go pick up Seven because King has beaten him up.
Starr and Chris arrive at King's house where Kenya and her little sister Lyric are tending to Seven's wounds. Iesha callously tells the kids to beat it since King is coming back soon and she is just trying to drink. The kids head out the front door but see King arriving in his car. Iesha sends the kids out the back door for safety.
The group arrives near City Hall where a massive crowd is growing for the protest. As they approach City Hall, the crowd is halted by a SWAT team. Starr tells Chris to get Kenya and Lyric out of there for safety. She then spots April, who hands her a megaphone so that Starr can be heard. Starr stands high up and announces to the crowd that she was the witness to Khalil's death, but so is everyone else in the crowd. While the people are moved, the police start firing tear gas grenades. Starr picks one up and hurls it back toward them. Starr and Seven run out but are blinded by the gas. Two friends of Maverick find the kids and put them in their pickup, along with two others. Starr tells them to go to her father's store to get milk to soothe the tear gas burns.
The men bring Starr and Seven to Maverick's shop to pour milk over their faces. The men leave Starr and Seven, which King sees. As Starr listens to messages from her mother, King's goon lights the store on fire. Starr and Seven try to escape out the backdoor, but it's locked. Two other shop owners see the fire and try to help get the backdoor open. Maverick, Lisa, and Sekani arrive, and Maverick gets his kids out. King sees this and runs toward them. Maverick threatens to kill King and reaches into his back for the gun, only to find Sekani holding it and aiming it at King. That's when two white cops arrive and draw their guns on Sekani, to the horror of everyone else. Starr stands with her hands in the air to protect her little brother and yells to the cops asking how many more of them have to die for them to understand. Sekani drops the gun, and the police turn theirs away from him. King leaves the Carters alone.
King is later arrested after multiple testimonies, and his rule over the neighborhood is now over. Starr and Chris are on better terms and are stronger than ever. She is no longer friends with Hailey, but she is still friends with Maya. Seven graduates from high school and is set to go to college the next year. Maverick's shop is in the process of being rebuilt, and he and Carlos get along better now.
Starr goes to Khalil's home where Miss Rosalie tells Starr she can take whatever she wants from Khalil's room. She goes in and finds the "Harry Potter" wands that they used to play with. With her closing words, Starr vows to live up to her namesake and light up the darkness.