Laughlin, Nevada casino waitress Charlie Cale, a woman with the ability to tell if someone is lying, observes her maid friend Natalie Hill's abusive husband Jerry be ejected by head of security Cliff LeGrand. Manager Sterling Frost Jr. asks Charlie to help him scam client Kazimir Caine. Natalie discovers child pornography on Caine's computer. When she reports it to Frost, he deletes the evidence off her phone and has Cliff kill her and Jerry, staging it as a murder-suicide by using Jerry's gun. Charlie notices that Jerry's gun was in his right hand in a crime scene photo, contradicting where his ankle holster was, and she steals Natalie's tablet. She finds the deleted evidence in the tablet's trash and presents it to Frost, believing Caine was responsible for Natalie's murder. She realizes Cliff kept Jerry's gun when she sees footage of the metal detector not going off as Jerry was removed. She reveals to Frost that she recorded him setting up the scam poker game and sent it to Caine, irreparably damaging the casino's reputation. Frost commits suicide and Frost Sr. later calls Charlie, promising to kill her.

Charlie's car breaks down in New Mexico and she gives it to mechanic Jed. Both he and Subway worker Damian have a crush on convenience store clerk Sara, and Jed pushes him off his body shop's roof when he realizes Damian has won the lottery, finishing him off with a crowbar. He takes the lottery ticket and hides the body in passing trucker Marge's vehicle. She discovers it and tries to get rid of it, and Jed calls the police to frame her. Charlie's car is fixed, but Marge is blamed for Damian's murder and Jed claims the ticket as his own. After he lies about Damian never winning the lottery, Charlie reviews the body shop's security footage and notices it skips an hour. When she points out that the ticket's serial number does not match the time Jed claims to have bought it, he admits to the murder but has discovered that she is a person of interest and threatens to report her if she calls the police. As she leaves, a hidden camera radio show leads her to realize that a trucker she sat next to during Damian's murder would have caught the crime on his dash cam, asking his friends to turn the footage in to the police. Sara misdirects an arriving Cliff and Jed burns the ticket as the police arrive to arrest him.

In Texas, a stray dog that follows Charlie eats barbecue at an outdoor restaurant run by the Boyle brothers. The business-minded Taffy Boyle demands Charlie pay off what it ate, so she takes a job there and bonds with head chef George Boyle. He is deeply moved when she shows him the film Okja and plans to give up his stake in the business. Unable to afford buying him out, Taffy pre-records a segment for his radio show and pretends to air it live while he seals George in his trailer and suffocates him with grill smoke, beating the dog when it attacks him as he leaves. Charlie finds the dog as she leaves town, realizing that the wood it was beaten with is the same wood that created the smoke that killed George and was only used by him. After confirming Taffy had time to kill George during the broadcast, she brings her findings to Mandy, George's wife, and realizes she is in on it. Charlie has station employee Austin impersonate Taffy over the phone to trick Mandy into thinking he is going to confess, prompting her to sell him out to the police. Austin plays her call on air in front of the police, getting them both arrested, and Charlie leaves the dog with him as she departs.

Charlie is hired by heavy metal band Doxxxology to sell merchandise on tour, befriending new drummer Gavin, who enjoys writing lyrics based on things around him. Vocalist Ruby Ruin is haunted by the band's only successful song, "Staplehead", only benefiting their former drummer, and is horrified when Gavin presents the band with perceived hit "Sucker Punch". The band rigs his amplifier to electrocute him when Ruby lets him sing "Staplehead" and they pass "Sucker Punch" off as their creation. Charlie realizes the lyrics are based on items in Gavin's trash, and learns that the band was wearing rubber soles after finding a camera Gavin set up to record his footwork. She is forced to flee when a video of her punching a band's promotional mascot goes viral, allowing Cliff to track her down. "Sucker Punch" revives interest in Doxxology, but their lawyer informs them that the song's melody is lifted directly from the theme of Benson, resulting in a copyright lawsuit. Charlie sends a true crime podcaster that she met earlier her evidence that the band killed Gavin, and an episode is made about them.

Charlie befriends ex-felon residents Joyce Harris and Irene Smothers while working at a retirement home, who tell her of their past as cult members and lovers of their leader Gabriel. A police raid sent them to prison, and they recognize a new resident as Gabriel, who reveals he sold the cult out to the authorities and begs forgiveness. Irene sneaks into his room and poisons him, switching his wearable heart monitor and having Joyce tase her to trick the orderly into thinking he died of cardiac arrest. Charlie bumps into his "nephew" Luca Clark at his funeral, who admits he is an FBI agent with witness protection and explains that Irene and Joyce were actually arrested trying to bomb a Model UN meeting. A nosy resident tells Charlie that she saw Joyce tasing Irene, prompting them to kill her with a bomb. Charlie informs them that Gabriel's heart rate did not change when staff defibrillated him. They try to kill her, but the waiting FBI are alerted when she tases herself while wearing a heart monitor. When Charlie later starts a golf cart, she narrowly avoids death when it explodes, giving the women the middle finger as they are taken away by the police.

Actress Kathleen Townsend visits her longtime nemesis and former costar Michael Graves to ask him for help putting on a one-night play and revitalize her career, and he reluctantly accepts after his wealthy wife Ava encourages him. Fed up with each other during the show, they rig a light and trapdoor to kill each other. Michael has a heart attack when the light misses him, and Ava falls to her death through the door when she runs to give him his medication. The show turns out to be a publicity stunt as part of their plan to reveal their love for each other, having killed Ava so they could be together. The show's popularity prompts Kathleen to give it another day, while the third actor Rebecca extorts them for money when she finds the script for a planned argument. Charlie, a waitress at the venue, determines the two are in love through their performances and learns that they rigged the stage earlier. Kathleen tries to kill Rebecca via her fatal nut allergy by contaminating a food bowl, forcing Charlie to drag her offstage and pretend it is part of the play. Kathleen and Michael argue backstage, and Charlie records their admission of guilt and shows it to the sheriff in the audience. Knowing she will soon be arrested, Kathleen uses this to give a stellar final performance.

Aging Tennessee racer Keith Ownes loses to young Davis McDowell. Owens, suffering from shaking hands when he races, announce his intent to retire. His daughter Katy beats Davis in several rounds of go-karting, starting a feud between the two men. Owens sabotages Davis's car, but he witnesses this and sabotages it further. At a practice session, he lets Katy drives his car and it crashes, putting her in a coma. Having befriended Charlie and knowing of her lie detection ability, he shifts the blames to Owens, who publicly confesses his guilt when confronted. Charlie notices Davis lying about Katy's crash being an accident, and he catches her looking through his garage. He tries to run her off the road after refusing to answer his questions. At his next race, she tells him that Katy woke up and will race him after she recovers, and as she leaves, his hands start to shake.

Max, the founder of visual effects company LAM, confronts co-founder Laura over something he found in old footage, so she poisons him. Charlie befriends the third co-founder, Arthur Liptin, and begins working as his assistant. He admits that he still blames himself for the death of Lilly Albert, an actress who drowned on the set of LAM's first film. Laura asks Arthur for a bust of Max's head to grieve, but actually uses it to pass the facial recognition software on his laptop and delete a piece of footage from the archives. Arthur watches the physical copy of the footage and realizes that Laura caused Lilly's death, burning the reel when confronted but keeping the incriminating frames, only to die from poisoning upon returning home. Charlie realizes Laura is lying about Max and Arthur's deaths. Laura takes Arthur's things for a memorial exhibit at LAM's offices but misses the hidden footage, which Charlie retrieves. As Laura memorializes Arthur and Max at the opening, Charlie plays the footage on the screen behind her to the large crowd. Laura flees, seeing visions of Arthur and Max and following the latter over a balcony to her death.

While stranded in the Colorado mountains, Charlie picks up kleptomaniac drifter Mortimer "Morty" Bernstein and crashes her car while trying to avoid a deer. When Morty does not return with a tow truck, she tries to flag down a car and is hit by Trey Nelson, who is violating his house arrest while on parole. He drives her to his estranged friend Jimmy Silva's motel and has him help bury her outside. Charlie wakes up with a broken leg and crawls to the motel door just as Morty arrives in her car. As a blizzard traps the four in the motel, Morty realizes that Charlie found a bone outside and wonders if it could belong to Chloe Jones, a local woman who vanished a decade prior. She finds Chloe's remains where Charlie was buried, and she agrees to keep quiet in exchange for Trey's car when confronted. He beats her and pushes the car off a cliff with her inside. Jimmy drugs Charlie and he and Trey argue about their roles in Chloe's death. Having feigned being drugged, Charlie tries to take her car keys, convincing Jimmy that Trey killed Chloe when caught. Trey kills him in a struggle and stabs Charlie, burying them with Chloe and arriving home just in time to meet with his parole officer, only to realize that Charlie swiped his ankle monitor when they fought. In the hospital, Charlie learns that Trey was arrested and Morty was mistaken for her. Cliff waits for her outside.

Tired of his year-long pursuit of Charlie, Cliff makes a deal with Frost Sr.'s rival Beatrix Hasp to kill him. Alerted to Charlie's location by news of her "death," he finds her room and calls Frost Sr., who orders him to wait months until she heals. Cliff forces her into the car when she leaves, trying to goad her into killing him with his gun and taking her to Hasp's Atlantic City casino. Frost Sr. reveals that he has all casinos wiretapped and learned that Frost was dealing with Hasp, no longer blaming Charlie for his death and asking for her help with Hasp. The lights go out and Cliff kills him with the gun Charlie touched before planting it on her. She hides out in her estranged sister's house, who gives her the keys to their father's boat and asks her to leave, not wanting her family involved with Charlie. She finds the boat too damaged to escape on and reluctantly calls Cliff, who asks her to meet him on his boat, calling the police beforehand to have her arrested. Arriving, she finds poker chips from Hasp's casino that glow under blacklight and realizes he used them to see Frost Sr. in the dark. She fights Cliff off and jumps ship just as the FBI arrive, Charlie having sent Sterling Frost Sr.'s recording of Frost Jr. ordering Natalie killed. Cliff testifies against Hasp and Charlie's name is cleared, only for Hasp to call her and give her the choice between working for her or dying. Charlie destroys her phone and flees.