Maggie Gyllenhaal could’ve let the scene slide by, not devoting as much energy and time to it as was necessary. But for all that she had invested in “Sherrybaby” — not only starring in the indie but helping to raise production coin, casting and marketing — there was no way to go half-assed now.

In the film, Gyllenhaal plays Sherry, a drug-addicted ex-con who’s finally out of jail and trying to get her life back together. First and foremost for Sherry is reconnecting with her daughter, Alexis, who is being cared for by Sherry’s brother and sister-in-law.

Having problems finding her place in functioning society, Sherry takes Alexis away and secretly plans to drive to Florida with her. En route, however, she realizes that by stealing her daughter, a chance for a normal life would be non-existent. Standing outside the car, she decides to go back to her brother and keeps plugging away at staying on the straight and narrow.

“The script was astonishingly good, and that scene was not finished,” says Gyllenhaal. “We got there, and it wasn’t figured out. That’s the moment where she has to stop looking and being hopeful in a reckless way and acknowledge it’s not working. That scene could’ve been an after-school special.”

It wasn’t, and Gyllenhaal’s insistence on making it just right paid dividends for the pic, which was directed and written by tyro filmmaker Laurie Collyer. “Sherrybaby” preemed at this year’s Sundance Film Fest and was accompanied by strong reviews.

A.O. Scott of the New York Times added: “What distinguishes the film from its many peers is the quality of Ms. Collyer’s writing and the precision of Ms. Gyllenhaal’s performance. She treats the character neither as a case study nor as an opportunity to show off her range, but rather as a completely ordinary and therefore arrestingly complicated person.”

Gyllenhaal’s participation in “Sherrybaby” was somewhat coincidental. Collyer and Gyllenhaal’s mother, Naomi Foner, were both at the Sundance Institute, and when Foner read the script, she suggested to Collyer to send it to Maggie.

“I can tell 20 pages in if it’s compelling to me,” Gyllenhaal explains. “I thought the script was so well written and was drawn into it. I didn’t even think for a second, though, how rough it was going to be to get the movie made.”

Favorite film of the past five years: “Cache”

Actor who impressed you greatly after working together: “Emma Thompson. She’s so easy and respectful of everyone and totally prepared and fun.”

Next project: “Nothing. Just spending time with my baby.”