After hiding her face in public for eight years, Ms. Agarwal began a different kind of coming out. She filed a police report against her attacker, who was sentenced to 10 years in prison — a rarity in India. She pushed lawmakers to restrict the sale of acid (including the kinds most commonly used in these attacks, hydrochloric and sulfuric) and became the director of Chhanv Foundation, a nonprofit dedicated to helping acid attack survivors. In 2014, she was honored at the White House by the former first lady Michelle Obama. Much of her journey is recounted in the movie, which fictionalizes Ms. Agarwal’s story but adheres to the heart of its substance.

The script, which had been turned into a screenplay by the director Meghna Gulzar, caught Ms. Padukone’s eye immediately. In 2018 she was finishing up filming for two period dramas, and looking for something emotionally lighter. But Ms. Agarwal’s story was too compelling. (Ms. Padukone has been in dozens of Indian films but may be best known in the U.S. for starring alongside Vin Diesel in the 2017 movie “XXX: Return of Xander Cage.”)

“It’s not very often where you know in literally a couple of minutes that this is a movie you want to commit to,” Ms. Padukone said, “where reading through the first few pages, you’re like, ‘Boom, this is it, and I want to do this.’”