Lucy Moro and her older sister Martha are anti-death penalty protestors, fighting for the acquittal of their father Simon, who is on death row for the murder of their mother eight years ago. The sisters live in their parents' house in a small Ohio town, and travel to various states in a mobile home, together with their little 10-year-old brother Ben. At one demonstration outside a prison in Illinois, Lucy meets Mercy Bromage, a lawyer whose father is a police officer. Despite the political tensions between the two, Lucy and Mercy grow closer to each other. They begin to keep in contact over the phone and over Skype. During a solo excursion to a demonstration in Missouri, Lucy and Mercy start a romance. Meanwhile, Martha is determined to free their father and manages to hire a lawyer, who is then able to get a four-month stay of execution to look for legal loopholes or any new evidence to re-open the case. When the last of Martha and Lucy's legal appeals is denied and the evidence continues to point towards Simon, a distraught Lucy travels alone to Illinois to visit Mercy. There, she learns that Mercy still lives with her parents and she also has a boyfriend. Feeling used and betrayed, Lucy breaks up with Mercy. Regardless, Mercy attends Simon's execution with the sisters. Six months later, Lucy is working as a waitress in California when she bumps into Mercy. Mercy attempts to rekindle their relationship, but Lucy rejects her, saying "I just don't think you can come back into someone's life like this". Regardless, the two awkwardly set up a date for later.
In August 2016, Ellen Page, Kate Mara, Pablo Schreiber, Elias Koteas and Amy Seimetz were cast in the film, with Tali Shalom Ezer directing from a screenplay by Joe Barton. Christine Vachon and David Hinojosa served as producers under their Killer Films banner, alongside Mara and Page, while Robert Halmi Jr. and Jim Reeve will serve as executive producers through their Great Point Media banner along with executive producer Karri O'Reilly. In September 2016, Brian Geraghty joined the cast of the film, replacing Schreiber.
Filming
began on September 19, 2016.
Release
The film had its world premiere at the Toronto International Film Festival on September 9, 2017. It was released in the United Kingdom on May 17, 2019, by Signature Entertainment, and was released in the United States on July 5, 2019, by Lionsgate.
Reception
On review aggregator website Rotten Tomatoes, the film has an approval rating of 94% based on 18 reviews, and an average rating of 7/10. The website's critical consensus reads, "Though My Days of Mercy knotty romance drifts into melodrama, it's grounded by Ellen Page and Kate Mara's exceptional chemistry." The film was selected to compete for the Premio Maguey's Best Film award at the 33rd Guadalajara International Film Festival, where Page was awarded in the Best Performance category.