Annie Baker is one of the great American theater artists of her generation. Her plays—like the adult-education theater class dramedy Circle Mirror Transformation, the eerie and wistful ghost story John, the Pulitzer-winning look at the employees of a small-town movie theater The Flick—challenge notions of traditional plotting while also digging deep into ordinary humanity. Her work is at once plainspoken and breathtakingly poetic; watching an Annie Baker show often feels like seeing a magic trick.

Thus there was great anticipation when Baker’s first film, Janet Planet, was announced, as well as some apprehension. Could her signature style survive the demands of a movie—both technical and structural? What would film offer her that theater cannot? Things are both lost and gained in Janet Planet (opening in select theaters June 21), a self-contentedly small movie about a mother and daughter wandering through summer.

Julianne Nicholson plays the title character, an acupuncturist and single mom raising her 11-year-old daughter in Western Massachusetts in 1991. But that daughter, Lacy (Zoe Ziegler), is really the lead of the film. It’s mostly through her eyes that we come to learn about this little family’s world: its pleasures and aches, its specific habits and parameters.

At the opening of the film, Lacy makes a late-night phone call from summer camp, saying she thinks she might kill herself if her mother doesn’t pick her up and take her home. It’s a rather dramatic, and darkly funny, beginning that suggests more to come. But Baker keeps much of the rest of the film quiet, restrained. Janet Planet unfolds at a dreamy murmur, using soft strokes to paint a picture of a liminal time in childhood —the period of dawning awareness of a parent’s individual humanity.

Baker segments the film into chapters, telling micro-stories about the various people who drift into and out of Janet and Lacy’s orbit. There’s a boyfriend, Wayne (Will Patton), who is laconic and suffers from migraines and doesn’t appear to have much care for Lacy. A friend and local theater artist, Regina (Sophie Okonedo, warm and appealing as ever), briefly shacks up with the girls. And then there is Avi (Elias Koteas), another hippie theater person who captures Janet’s attention.

Not a lot seems to happen in these vignettes. But, of course, something rather large actually is: Lacy is watching. She is learning ever more about her mother’s wants and frustrations, her patterns of error or misjudgment, her needs as they exist separately from her daughter. Baker grew up in Western Massachusetts and was born about when Lacy would have been, and is perhaps reflecting on her own awareness at that age: how much she both did and didn’t understand about the adults in her life. In learning things about her mother, through interaction and observation mimicked by the film's hovering closeups, Lacy is also learning about herself, about how people bounce off of and draw close to one another throughout their lives.

As maybe is suggested by the film’s title, there is a great universality to all this rumination; we can probably all remember moments from childhood when we felt we had a new comprehension of our family or our community, even our world. Baker communicates these revolutions with a very light touch, perhaps too light sometimes. One yearns for more from these charmingly idiosyncratic people, to hear them fully express themselves. The film seems, at times, like a timid first attempt, not wanting to disrupt its delicate construction with anything so intruding and conclusive as plot or exposition.

In many other ways, though, Baker proves herself to the medium born. The natural world is palpably conjured in Janet Planet, all the particular noise and light of Massachusetts in summer. (As a native of that state, I felt utterly transported back to place and time.) Baker handles her actors beautifully, giving them room to inhabit the spaces of the film as if they’ve always been there—she has done especially well in casting Ziegler and creating a credible reality through which the young first-time actor can organically maneuver.

And Baker builds to a deeply affecting closing shot, a picture of a kid on the brink of something, turning a corner toward adolescence and all the coming evolution of her relationship with her mother. As is true of Baker’s plays, Janet Planet envelops its audience with a lulling mood before delivering a closing punch of meaning, a kind of summation of theme and intent that casts a clarifying light on all that you’ve just watched. Oh, that’s what this hushed thing has been showing us all along—just as Lacy does, we finally get it.