Allison Dubois loads groceries into the car, a routine task on a seemingly normal day. That is, until she is in a dream of a man at a bus stop running from a car, and she wakes on a desolate street, roughed up, her car gone and no memory of how she got there. She feels a paper in her hand, unfolds it. It reads, "1927 Hennypin." She opens her cell phone to see that it's near midnight and she has 27 missed calls. Her phone rings; it's Joe, relieved to hear her voice. Allison doesn't know where she is but reads a street sign to Joe. She has no idea what's happened.
Joe finds Allison and takes her to the hospital. The doctor says she has no signs of concussion or sexual assault. However, she's still lost six hours of her life. The doctor says that she most likely experienced something traumatic during that time and her mind is blocking it out to protect her. He says it will come back to her eventually. The next morning, her family makes her pancakes to show Allison how glad they are to have her back. Ariel shows Allison an application for her learner's permit to drive, which Allison signs.
Det. Lee Scanlon arrives and says they questioned everyone who was at the supermarket but nobody saw anything. Since Allison can't remember anything after approaching her car, Scanlon thinks she was attacked after leaving the parking lot. He notes the lump on her head and suggests she stay home for a couple days. Allison shows Lee the address, which isn't in her handwriting. He'll check it out. During a nap, Allison dreams again about the car chasing the man at the bus stop and is awakened when Scanlon calls to say a squad car will arrive shortly to take her to the morgue.
At the morgue, the man from Allison's dream lies dead of a hit and run from last night. The accident occurred at the address Allison gave to Scanlon. The victim's name is Diego Moleno, an undocumented alien who worked as a day laborer at a lumber company. Allison can't remember how the address got into her hand. At home, as Joe cleans Allison's wound, he says he's excited to teach Ariel how to drive. He asks Allison if she's okay that he teaches her instead of Allison. Allison teases him about it.
Allison dreams about a wounded Diego dying on the sidewalk. She exits her car and runs to him. He asks her, "Why?" Hysterical, Allison says, "Look what I've done! It's all my fault!" She wakes, equally hysterical because she thinks she killed Diego. Joe is skeptical, which angers Allison, who thinks he doesn't take her seriously. Allison thinks she's being spared from remembering the actual impact. Joe still doesn't believe she ran Diego over. Allison wants to call Devalos but Joe stops her, saying to wait until they find evidence before letting a couple of dreams turn their family's life upside down.
The next day, Devalos tells Allison that someone used her credit card during her six-hour blackout period. They watch surveillance video from a big box construction store where to her shock, Allison sees herself purchasing a hand saw and Ziploc bags. They even have a signed receipt, but the signature doesn't look like Allison's handwriting. Devalos says she can't deny it's her on the tape and that she should be relieved that up to 9:00 PM that night she was just shopping. He thinks she wasn't attacked, just knocked out and wandered off. Allison isn't sold on that idea.
Joe starts his driving lessons with Ariel and tells her to follow his instructions. He's obviously more nervous than she is. Devalos tells Allison that her car is in the tow yard and gives her money to get it out. Later at home, Allison shows Joe that there isn't a mark on it. Joe says that's because it wasn't involved in a hit-and-run accident like she feared. He adds that Ariel already knows everything about driving and that she did fine.
Allison dreams that she's running from a downtown trucking company and throwing her purse in the trash bin. She starts awake, and then wakes Joe to tell him she's going there to retrieve it in case they haven't picked up the garbage yet. She was able to locate the address through the sign she saw in her dream. At dawn, outside the company, she digs through the bin and finds her purse. In her car, she searches the contents and is horrified to find a severed hand inside a Ziploc bag.
At the station, Scanlon tells Allison that the hand belongs to Maria Vargas, a bookkeeper at Green Highway Trucking. Scanlon learns that Maria has been found dead at her address. Inside her apartment, Maria lies bloodied from a beating, with one hand missing. Scanlon shows Allison a note that Maria was clutching. It reads, "Hector Alvarez did this to me." Scanlon tells Allison to go home and he'll call her when they learn more. At home, Ariel asks Joe to drive with her but he's not as enthusiastic. She thinks he doesn't like to drive with her, but he assures her that's not the case.
Scanlon calls Allison to tell her that the ME says it's highly unlikely she killed Maria. Allison, who had been worried that she was involved but just couldn't remember, is relieved that forensics revealed the attacker was at least a foot taller than she was, very strong and left handed, whereas Allison is right handed. Scanlon says that the name Hector Alvarez didn't ring any bells with them, but he was really familiar to the FBI. He tells Allison that there's a bit of bad news. Her fingerprints are on the note with Alvarez's name on it. Allison wonders how that's possible.
Allison dreams she's in the trucking office holding Maria's severed hand, scanning its fingerprint to gain access to the company's computer. Access granted, she bags the hand and puts it in her purse. She finds a phone number and inputs it into her phone when Hector asks who she is and why she's in his office. She calmly says that he killed her earlier tonight, then stabs him in the shoulder with scissors. They fight, he slams her head into a desk. She whacks him with his gun and knocks him out, then flees outside and dumps the purse in the trash bin.
At five in the morning, Allison searches her phone for the number that she put into her phone. Joe wakes and wonders what she's doing up so early. She tells him she didn't lose the six hours, they were taken from her by Maria, who had some unfinished business to tend to. It was Maria, inside Allison, who did all those things, including sawing off her own hand so Allison could gain computer access. All to get one phone number that she shows to Joe. Joe dials it, but it's no longer in service. Allison doesn't understand.
The next morning, a bleary-eyed Joe drives with Ariel. She is still sensitive to the possibility that Joe isn't enjoying driving with her. When she's with her driving instructors, all she thinks about is what her dad would do, and he's letting her down by thinking this is about him instead of her. He apologizes. Still upset, she proceeds through an intersection and almost has a collision. This patches things up and they decide to not mention it to Allison.
At the courthouse, Allison repeatedly dials the disconnected number. Devalos says the FBI found Hector, who they've learned is a human trafficker, at the hospital. At the hospital under FBI guard, Alvarez lies a coma as his son sits at his side. Devalos says Alvarez drove to the hospital and passed out outside, and that Maria's blood was found on his shirt. The FBI hadn't been able to charge him with anything until the murder. Allison tells Devalos about Maria "borrowing" her for six hours.
Devalos comforts a worried and guilt-stricken Allison when he says no one was looking for her blood at the scene, and that she wasn't in her mind when she stabbed Alvarez. At home, Joe agrees, saying it was self-defense even though she wasn't in her own body. Allison worries how she'll explain to a jury that a woman took over her body to get a phone number that doesn't even work. Joe tells her to stop making herself crazy and get some rest.
Allison dreams about Maria entering her apartment, talking to Diego on the phone about people dying. She says she has to call the police even though she's scared of Alvarez. She writes down the Hennypin address and says she'll pick him up soon. But, Alvarez has snuck into her apartment and heard her. He confronts her. She says she can't let the 18 immigrants, including women and children, die in an abandoned truck in the desert. Alvarez is fine with it because there's an undercover FBI agent traveling with them. He then bludgeons Maria to death and goes to kill Diego. Allison wakes.
At the courthouse, Allison tells Devalos about the immigrants and undercover FBI agent. She says Hector called the driver and told him to dump the truck and leave the people in it. Maria wanted to help them but she didn't know where they were. That's why she needed the driver's number off the computer. Devalos alerts the FBI and checks out the number. Hours later, Devalos tells Allison and Scanlon that helicopters are searching the area. He confirms they haven't heard from their agent in four days, and that the phone number led to a disposable phone bought with cash.
Allison dreams that as Maria, she stabs Alvarez and then calls Alvarez's son, who answers the phone crying. She tells him to save the people, then passes out. The next day at the courthouse, Devalos watches a news story about the 18 rescued immigrants and tells Allison she saved a lot of lives. He says the son, clearly tortured about it, immediately disclosed the truck's whereabouts. He'd left them with two cases of water and a bag full of candy bars. Devalos says that soon after he left, Alvarez's son smothered his father to death with a pillow.