The film starts on what appears to be an 1800's era antebellum plantation. Confederate troops led by a man named Jasper (Jack Huston) bring in a few runaway slaves. One of them, Amara (Achok Majak), runs away again in terror after watching the other men strap a device to another slave, Eli (Tongayi Chirisa). Jasper chases after Amara on horseback and brings her down by lassoing a noose around her neck. She begs to be killed instead of returned to the antebellum, and Jasper obliges her by shooting her in the head.One of the captured women, Eden (Janelle Monae), is brought into the home of her owner, a Confederate general known only as "Him" (Eric Lange). He beats Eden and orders her to say her name. When she cannot, Him grabs a branding iron and burns it into her back, causing her to scream in agony before weakly crying out her name.Six weeks later, a new group of black people are brought in to the plantation. Jasper orders the group to not speak unless they are given permission. Jasper's wife Elizabeth (Jena Malone) brings her daughter (Arabella Landrum) to pick one of the women in the group, whom the little girl names Julia (Kiersey Clemons). When Eden takes Julia with her, she asks Eden where they are and what is happening, but Eden tells her to keep quiet.Eli goes to Eden's house later to ask when they can escape again, but Eden appears to have given up hope. She walks carefully across the floor to see which boards do not make noises when stepped on. Julia then goes to her home, where she seems to already know who Eden really is. She wants to try and escape as well, as she is pregnant, but Eden shows her the branding scar to show that it is better not to anger the people in charge. Julia expresses disappointment in Eden, saying she is not a leader.The slaves are forced to work during a gathering of Him and his troops, where he boasts about preserving their way of life for the future. Two young soldiers, Purcell (T.C. Matherne) and Daniel (Robert Aramayo), observe Julia, and Daniel expresses attraction toward her. Purcell encourages him to speak to her, and Jasper comes in and orders Julia to wait in Daniel's cabin. When Daniel goes to find her later, Julia tries to appeal to what she thinks is his innocent nature since he appeared to be kinder than the other men, but he proves to be just as terrible when he strikes Julia for speaking to him without permission. He kicks her in the stomach before leaving.The next day on the plantation, Julia suffers a miscarriage. She cries out in pain and distress, and Eden goes to help her. Jasper attempts to antagonize them, but Eli keeps him back briefly by calling him a cracker. After letting Eden help Julia, Jasper confronts Eli over the matter, with the other soldiers getting ready to fire if they need to, but he instead sends Eli to clean out the shed. There, he finds the burnt remains of Amara, which he recognizes from her cross necklace. Eli breaks down.That night, Eden tries to sleep. She starts to hear what sounds like a cell phone ringing. She then appears to wake up from what seemed like a bad dream. Here, Eden is revealed to be an author and activist named Veronica Henley, married to Nick (Marque Richardson) with a daughter, Kennedi (London Boyce), all of whom live in present day Atlanta, Georgia. Veronica is well noted for speaking out against the treatment of black Americans, causing her to butt heads with pundits. As she is preparing for an upcoming trip, she sits to have a video conference with another woman... and it's Elizabeth. She uses condescendingly racist dialogue while discussing Veronica's book and its themes. Elizabeth also describes herself as a "talent scout" while noticing Kennedi, which makes Veronica uncomfortable.After going off on her trip, Veronica meets up with one of her best friends, Dawn (Gabourey Sidibe), as she visits Veronica's hotel room. She expresses to Dawn some of her frustrations and insecurities with her home life. After Dawn leaves, a mysterious man arrives to bring Veronica flowers but won't say who they are from. Based on the note that's left, she assumes they're from Nick.Veronica steps out of her room and runs into her other close friend Sarah (Lily Cowles), who is joining her and Dawn later that night for dinner and drinks. Meanwhile, Elizabeth sneaks into Veronica's room, tries on her lipstick, and walks around the room to observe before turning the tag on her door so she won't get turn-down service. Veronica then attends a conference where she speaks before an audience of black women, all of whom are moved and inspired by her words. As she goes back up to her room, the girl that appeared to be Elizabeth's daughter is in the elevator with her and creepily tells her she shouldn't speak unless given permission, but Veronica thinks it's just a game.Veronica later joins Dawn and Sarah. On the ride to the restaurant, Veronica talks to Nick and thanks him for the flowers, but he says it must have been a fan. Dawn is abrasive toward the staff since she demands the best table and wine. During the night, an unseen man (implied to be Jasper) watches the women all night until he sends a vodka cranberry to Dawn. He then approaches her personally to compliment her, and while flattered, she takes the time to critique his attempt, since she thinks that drink pales in comparison to the wine they are celebrating with, but she gives the man her number just in case. The ladies then prepare to part ways, with Veronica heading into an Uber. Midway through the trip, Veronica gets a call from a woman who says she is her driver waiting outside the restaurant, but she thinks there's a mistake. Veronica then looks at the driver to see that it's Elizabeth. Jasper then appears from behind her to grab her. Veronica struggles to break free, but he ultimately knocks her out.Veronica wakes up back on the plantation, where she is still hearing the phone ring. Outside, Him - actually Senator Blake Denton - answers the phone and speaks to someone over how Nick has been all over the news with Kennedi searching for Veronica, and he promises to take care of it. Veronica pretends to be asleep while Denton says he won't let anyone take her away from him.The next day, Veronica finds that Julia has hung herself. In her despair, she decides that tonight will be the night that they escape. She waits until Denton has fallen asleep, and she manages to sneak outside quietly. Eli finds her and helps her get the cell phone to call for help. They try to make it to the cabin to get a signal, but Purcell and Daniel are out after drinking, forcing the other two to hide and drop the phone. Daniel picks it up, and after Purcell leaves, he stops to urinate. Eli cracks him in the face and leaves Daniel to choke on his blood while they get the phone. They try to make it to the cabin, but Denton attacks the two of them. A fight ensues with Eli hitting Denton to keep him off Veronica, but Denton kills Eli with a hatchet. Veronica hits Denton with a tea kettle before getting his phone. Denton steps out but Veronica stabs him in the gut with a bayonet. She unlocks his phone and manages to call Nick and let him know she is alive, and she sends him a location pin to give to the police. Veronica then goes to Eli's body and addresses him by his real name, Professor Tarasai.Veronica rolls Denton into a confederate flag and brings him to the shed. He weakly tells her that there will still be more like them, but she scoffs at him. As she goes to get a torch, Jasper finds her, but she tells him that Denton is hurt. Jasper and another guard run into the shed, where Veronica locks them in there and sets the logs on fire to burn all three of them to death. She then rides on horseback as the other soldiers give chase through the woods. After losing most of them, Elizabeth pursues Veronica on her horse. She taunts Veronica and states that Denton (who was really her father) personally picked Veronica because she went against his whole campaign and agenda, while Elizabeth picked everyone else herself. Veronica lassos a noose around Elizabeth's neck, but Elizabeth slashes at Veronica multiple times until Veronica gains the upper hand and beats Elizabeth's face. Veronica then rides the horse while pulling Elizabeth until she slams her head against a statue, breaking her neck.Veronica continues to ride as the sun rises and the soldiers continue their re-enacting. She rides outside the gates of the plantation, where it's revealed that Antebellum is a Civil War re-enactment park. Veronica rides out on her horse to find other people, just as the police arrive, and she appears relieved. The police and feds rescue the kidnapped black people and bulldoze Antebellum to the ground.