Grade: 4.0/5.0

Content warning: gun violence.

It’s too bad Shailene Woodley, playing therapist Anna, only has a couple minutes of screen time in “The Fallout.” Those minutes, however, are pivotal to writer-director Megan Park’s film, which unfurls predictably in the wake of a high school shooting that leaves Vada (Jenna Ortega) shaken to her core. While predictability is usually the bane of an enticing story, “The Fallout” is sneakily aware of itself, lulling viewers into its steady rhythm then pouncing on them come the close.

The warning signs not to rest easy with “The Fallout” are everywhere. The first comes a short while after Vada spends the duration of the seemingly unending shooting sheltering on top of a toilet with Instagram-famous Mia (Maddie Ziegler). The shots ring out, each nailing in the trauma, though there is something underwhelming about Quinton (Niles Fitch), the student who slides into the stall they share, covered in his brother’s blood — his character seems incomplete, forgotten. Park has an ace up her sleeve though: an ingenuity that calculates her gutting film, one that only pulls the facade, the half-truths that each of her characters inhabit, into gruesome focus at the very end.

It’s nothing but expected when Vada shoots awake the morning after “the incident,” as Anna calls it, from a nightmare. Park captures the moment — just more than a couple seconds — with a subversive jump scare that might be more at home in a Blumhouse production, one-upping commercial horror flicks. The second time Vada sleeps, you think you’re ready for the same scare, but Park gets you again.

Coincidentally, “happens again” is the tagline “The Fallout” is trying to get across, though that only becomes apparent once “The Fallout” wraps. Maybe the whole film, not just those moments that inspire inklings of an eviscerating end, should be taken with a grain of salt, as when Patricia (Julie Bowen), Vada’s “anxious” mom, cautions Vada’s little sister not to get too attached to Anderson Cooper. In its own belated way, the film warns of becoming too attached to life itself, traumas and joys — there will always be another tragedy, be it a shooting, a car accident or a falling tree trunk.

To get “The Fallout” to that point, Park pours out her sharp sense of emotion, spooled together by cinematographer Kristen Correll. One sequence finds Vada shaking badly for so long that she seems oblivious, while more scenes show Vada and Mia, who are pushed together by fate and held together by unsteady flirtation, coping with the bottle. The two drink and smoke frequently at Mia’s home, where her parents, successful artists, are always out of town on business, not even there after the shooting.

Yet, Park decides not to stop at the immediate impacts of a shooting. These are contemporary high schoolers, ones who know how a smartphone works, what Instagram is and, dismally, what to do when a shooter comes to their school. Park contains all that, using everyday texting to tell as much of the story as personal interactions do. Vada and those surrounding her have a sophomoric energy to their flexibility (what adult habitually flails their legs in the air as they stand up), complemented by the film’s aesthetic. The curtain lights behind Vada’s bed are trivial, but they bring her comfort in a way adults might not understand.

That attention to the finer points of Vada’s life turns incomplete character arcs into brutal sincerity. Park delivers a withering blow to our and Vada’s comfort and sanity, and it no longer matters that these characters are missing pieces. What matters is that they are trying their hardest to live, to recover from their hellish experience — the same one thousands of other high schoolers have and will experience across the country.