We see Instagram pictures of a young woman named Charlotte Buckwald (Meredith Hagner) on her wedding day, sharing her happiness with her friends. Ingrid Thorburn (Aubrey Plaza) is in her car scrolling through the pictures while crying. She gets out of her car and storms into the wedding reception, walking up to Charlotte and pepper-spraying her in the face for not inviting her to the wedding. Ingrid tries to run away but she gets tackled by security.Sometime later, Ingrid is in a mental hospital where she writes letters to Charlotte, still under the assumption that they are friends. Upon her release, Ingrid goes to the supermarket where a friend of Charlotte's sees her and unsubtly comments to someone on the phone about how Ingrid was in the hospital and how she and Charlotte were never actually friends, but Ingrid stalked Charlotte after she liked a comment of hers on Instagram. Ingrid keys the woman's car on her way out.Ingrid looks through a magazine with an article on social media influencer Taylor Sloane (Elizabeth Olsen). Ingrid becomes fascinated with Taylor and everything she posts. She writes a comment on one of Taylor's posts and later receives a response from Taylor.Ingrid withdraws a $62,000 inheritance from her late mother and moves to Los Angeles. She rents a house from Dan Pinto (O'Shea Jackson, Jr.), an aspiring screenwriter and Batman fanatic who also takes a personal interest in Ingrid.Ingrid starts going around town trying to find Taylor by visiting her favorite restaurants or hang-out spots. She eventually finds Taylor in a book store, but she is too awkward to approach her personally. Ingrid then follows Taylor home and she kidnaps her dog Rothko. When Taylor finds a flyer for a reward for Rothko's return, Ingrid calls the number and is able to finally meet Taylor in person, along with her husband Ezra (Wyatt Russell). After Ingrid declines the reward money, the couple invite her to join them for dinner. Ingrid learns that Ezra is a painter, and she purchases one of his paintings. Taylor also invites Ingrid to join her at Joshua Tree.Ingrid asks Dan to borrow his truck for the trip on the condition that she read the part of Catwoman for his Batman screenplay.Taylor joins Ingrid as she drives them to Joshua Tree. The ladies have fun and become well-acquainted. Taylor becomes alarmed when she finds a gun and cocaine in the glove compartment. The truck breaks down and they have to stop at a mechanic, where Taylor mentions to Ingrid that she secretly wants to purchase a small house next to her own place to turn it into a book and thrift shop. Taylor then asks the mechanic to take pictures of them for Instagram. On the way back home, Ingrid and Taylor do Dan's cocaine. They start singing along to a song on the radio when Ingrid gets distracted and swerves against a guard rail, scratching the truck.Ingrid returns the truck to Dan in the morning as he is talking to the police since he hadn't heard from Ingrid. Dan is pissed, but Ingrid promises to make it up to him over dinner. That night, the two go out to eat. Ingrid tells Dan about how her mom had just passed away and how they were close. She starts crying, and he gets closer to comfort her. They begin making out and later go home to have sex with Ingrid wearing a Batman mask.The next day, Ingrid joins Taylor and Ezra as Taylor's recovering drug addict brother Nicky (Billy Magnussen) shows up. Ingrid instantly hates him when he clowns around on her. Nicky tells Taylor about a party in the area that they're invited to, which falls on the same night that she and Ingrid had plans. Taylor asks Ingrid if it's okay that she bails to spend time with Nicky. Ingrid says it's fine but she is clearly pissed.Ingrid sneaks into the party where Taylor, Ezra, and Nicky are hanging out with one of their friends, Harley Chung (Pom Klementieff). Ingrid walks up to them and tries to talk but she gets kicked out of the lounge they are in because she's not VIP.Ingrid is invited to a get-together at the Sloane house, and she invites Dan to pose as her boyfriend. Despite her telling him to stay away from Nicky, he and Dan hit it off. Ingrid tries to mingle with Taylor, but she is hanging out with Harley, whom she tells her plans regarding buying the house next to hers, making Ingrid more jealous when she overhears her. Ingrid later finds Ezra sitting alone by the pool. He expresses his displeasure with Taylor living this lifestyle of hers and being different than how she was when she first moved to LA.Ingrid goes looking for her phone and learns that Nicky has it. He managed to open it after seeing that Ingrid's passcode is Taylor's birthday. Nicky found all of Ingrid's photos and postings of her and Taylor, making him realize she is obsessed with his sister. Nicky blackmails Ingrid and demands $5,000 weekly from her, or else he will tell Taylor about this.Ingrid approaches a group of teens and pays one of them to punch her in the face. She returns to Dan with a black eye and makes it seem like Nicky hit her and is viciously demanding money from her. The two put on ski masks and "kidnap" Nicky as he leaves a club. He catches on quickly that Ingrid is behind this. They take him out to the desert to scare him and make him stop blackmailing Ingrid. Nicky fights back and takes Dan's gun that was aimed at him, only to find out it's a paintball gun. Nicky starts beating Dan until Ingrid hits him over the head with a crowbar. They leave him unconscious in the desert.Eventually, Nicky returns home and tells Taylor and Ezra about Ingrid. The two of them cut her out of their lives, but Ingrid continues to harass them with phone calls, with Ezra finally threatening to call the cops on Ingrid if she doesn't stop. Ingrid makes one more attempt to be closer to Taylor by buying the house she originally wanted to buy, using the last of her money (50 grand) to buy it. She doesn't have enough to pay for electricity and ends up living alone in the dark.Taylor and Ezra host a Halloween party next door. Ingrid crashes it by wearing a bedsheet and pretending to be a ghost just so she can find an outlet to charge her phone. The sheet falls off, and everyone sees Ingrid. Taylor tries to get her to leave, but Ingrid wants to talk to her real quick. Ingrid tries to apologize for what she did, but Taylor tells her they were never friends since everything Ingrid told her about herself was a lie. Ingrid tries to hit back with how Taylor is a fake person as well after hearing what Ezra said, but it doesn't seem to faze Taylor. Ingrid decides to leave them alone.Ingrid gathers a bunch of candles and makes a video to Instagram admitting that she's been pretending to be someone she isn't because she knows there's something mentally wrong with her, and that she hates who she is. She continues recording as she downs a bunch of prescription pills and alcohol before uploading the video. Ingrid then lies down and waits for death.Ingrid wakes up in the hospital. Dan saw the video and quickly got her medical attention, allowing her to survive. Dan then tells Ingrid that her video went viral, with thousands of people showing support for Ingrid with the hashtag "#iamingrid". As Ingrid scrolls through all the love and admiration she had been hoping for, a smile creeps up on her face.
Storyline
Ingrid Thorburn is an unhinged social media stalker with a history of confusing "likes" for meaningful relationships. Taylor Sloane is an Instagram-famous "influencer" whose perfectly curated, boho-chic lifestyle becomes Ingrid's latest obsession. When Ingrid moves to LA and manages to insinuate herself into the social media star's life, their relationship quickly goes from #BFF to #WTF.