‘Saint Frances’: A Chicago film star is born in locally made indie

One of the pure joys of this job is experiencing a breakout performance or discovering a new director destined for great things.

“Saint Frances” gives us both. Kelly O’Sullivan delivers an utterly authentic and real, funny and lovely, nomination-level performance in the lead role, and director Alex Thompson displays a fine gift for pacing and shot-framing and storytelling in this small masterpiece about a floundering 34-year-old underachiever who lands a summer job as a nanny to a precocious 6-year-old — and finds herself in over her head and yet born to the role at the same time.

Oh, and O’Sullivan also wrote the smart, layered, sometimes hilariously spot-on script. What. A. Talent.

“Saint Frances” is kind of a low-key, indie-vibe version of “Trainwreck,” with a sprinkling of thought-provoking forays into subjects such as faith and spirituality. Also, it’s just entertaining as hell.

O’Sullivan’s Bridget is working as a server in a diner and basically running in place through life, even as her friends and former classmates are married, having babies, enjoying a successful career — you know, all that grown-up stuff. Bridget isn’t in a relationship and she seems as if she hasn’t been in one for a long time — too much work and effort — but she has an active sex life, on her terms. At a party one night, she meets a similarly easygoing guy named Jace (Max Lipchitz) and takes him home, where they have sex that gets, um, a little messy. (Let’s just say both parties wind up with a little blood on them, and nobody got injured.)

In the morning, Bridget tells Jace he’s gotta go cause she has a job interview to be a nanny.

“You must really like kids,” says Jace.

“I don’t,” says Bridget.

Lily Mojekwu and Charin Alvarez are wonderful as Annie and Maya, respectively, a lesbian couple who live in a beautifully appointed home in the north suburbs and have a 6-year-old daughter named Frances (Ramona Edith Williams in a scene-nabbing performance) and a new baby on the way. After a spectacularly terrible interview, Bridget doesn’t get the job — but when the nanny who IS hired turns out to be a terrible fit, the desperate Maya calls her and asks if she can start, like right now, right this minute.

Bridget is comically inept. She can’t unfold a stroller. She doesn’t know how to talk to children. Her attempts at humor land with a thud. When a music school administrator who believes Bridget is Frances’ mother says, “We encourage parents to play with their ‘littles,’ ” Bridget says, “I don’t know how to do that.” (Longtime Steppenwolf star Jim True-Frost is terrific as the music teacher, who’s nearly as cool and likable and hippie-dashing as he believes himself to be.)

As Bridget and Frances slowly begin to build a bond (you didn’t think they were going to be at odds through the whole movie, did ya?), director Thompson expertly juggles multiple other storylines, from Bridget’s casual but not uncomplicated relationship with Jace to Maya dealing with the crushing weight of post-partum depression to Bridget confronting her lapsed-Catholic status after attending a baptism and finding herself in a church with Frances, who pretends to be a priest hearing Bridget’s confession. (Bridget notes it’s been, oh, 21 years since her last time in a confessional.)

I loved the use of Chicago and Chicago-area locations throughout this film; in the aforementioned scene, we see St. Vincent de Paul Catholic Church in Lincoln Park in all its breathtaking glory. The church is empty save for Bridget and Frances in the scene, and one can’t help but feel a twinge, knowing it will be empty this Easter Sunday and most likely for many Sundays to come after that.

“Saint Frances” also deals with abortion and its aftermath with a level of detail and honesty not often seen in the movies (though another recent release, “Never Rarely Sometimes Always,” explores the subject at even greater lengths, and with equal intelligence and sensitivity). The sequence has elements of dark comedy but also great tenderness, e.g., when Bridget is recovering and Jace reads a passage from a Harry Potter book to her.

Even when the film indulges in contrivances such a make-up and dance montage, it’s set to “I Hate Myself for Loving You.” And when Frances wonders why her music teacher kept calling her Joan Jett, Bridget says, “It’s a compliment” and explains how Jett made memorable music in part because she was angry and Frances asks, “Why was she angry?” Bridget responds, “Because she was born into a patriarchy.”

Nanny of the year.