Trama

When 93-year-old Thelma Post gets duped by a phone scammer pretending to be her grandson, she sets out on a treacherous quest across the city to reclaim what was taken from her.

93-year-old Thelma Post lives alone in Los Angeles. Her aimless but loving grandson Daniel "Danny" Markowitz often visits and looks after her needs despite not taking responsibility for his own life. Although Thelma is close with Danny, she finds his constant assistance patronizing.

A phone scammer calls Thelma posing as Danny, claiming he has been arrested. Thelma sends $10,000 to a local address as instructed. After a panic involving her daughter Gail and son-in-law Alan, Thelma finds out Danny is safe and she was scammed. Unable to get help from the police and unwilling to let the scammer get away with her money, Thelma evades her family and sets out to the address to retrieve it.

Thelma attempts to contact old friends for a favor but discovers most of them have died or moved away. She reluctantly enlists the help of Ben, a friend and widower living in assisted living whom she had been ignoring since her husband's death. They ride Ben's expensive 2-person scooter to the home of Mona, their elderly acquaintance. Thelma steals Mona's gun while Ben distracts her. Meanwhile, Danny, Gail, and Alan realize Thelma is missing and search for her to no avail. During an argument with his parents, Danny vents about his recent breakup with his girlfriend and his lack of skills aside from looking after Thelma, fearing he will go nowhere in life.

Thelma and Ben get lost in a shady neighborhood as they near the scammer's address. Ben insists on turning back, but Thelma refuses. They argue, and Ben chastises Thelma for her avoidance of him and her unwillingness to allow people to help her, which reminds him of how his impaired hearing prevented him from registering his late wife's fall years earlier until it was too late. Thelma admits she didn't need him, just his scooter. Ben's scooter is then destroyed by a reckless driver, prompting him to abandon Thelma. Thelma continues alone on foot, eventually suffering a fall. She realizes she can not get up on her own and gives up hope until Ben returns to assist her and the two reconcile.

Thelma and Ben reach the address, where a young man collects Thelma's money from a PO box. They follow him to a rundown antique store. Ben listens through their connected phones while Thelma sneaks in and discovers the owner, Harvey, and his grandson Michael running a scam operation in the backroom. Thelma demands her money back, but they refuse, and Harvey grabs her arm. Harvey, who relies on an oxygen regulator and his grandson, laments that his store is failing and has resorted to scamming people to stay financially stable. Thelma pretends not to know who they are and apologizes for being a nuisance. Once seated, she pulls Mona's gun on Harvey. Michael tries to escape but is knocked out by Ben outside. Thelma uses Harvey's computer while Ben holds Harvey at gunpoint but struggles with the banking system. She calls Danny for help, and he guides her through transferring the money while driving to pick them up. Michael re-enters the store, but Thelma tells him that Harvey talks down about him, leading Michael to abandon his grandfather. Thelma leaves Harvey $500 of the $10,000 transfer and scolds him for tricking people and not appreciating his grandson. Thelma and Ben exit the store triumphantly before being picked up by Danny.

Thelma is reunited with her family and they watch Ben perform in a play at the nursing home. She has a newfound respect for Ben, and they make plans to get together in the near future. While visiting her husband's graveside with Danny, Thelma assures her grandson that he will be fine when she is eventually gone. As Daniel drives Thelma home, they talk in the car about how incredible it is that the trees are still alive, no matter how gnarled their roots look. A mid-credits scene shows writer/director Josh Margolin having an identical conversation with his own (now-deceased) grandmother.