Zach Cregger’s “Weapons” opens with a mystery that sounds like a math word problem: If 17 children left their homes and disappeared at 2:17 in the morning, and there’s only one kid and one teacher left in their classroom — who is to blame? Because someone has to be at fault.

To puzzle through this particularly dark riddle with maximum mysteriousness, writer/director Cregger follows the main characters through the aftermath of this peculiar event. The first person he follows is the teacher, Justine (Julia Garner), the last, the student, Alex (Cary Christoper). In between, we ride along with Archer (Josh Brolin) the angry, grieving father of one of the missing kids, Marcus (Benedict Wong), the school principal, Paul (Alden Ehrenreich), a local cop, and James (Austin Abrams), the town junkie.

Confusion and grief about the case of the missing kids spirals into anger and harassment, spilling into and mixing with the mess of the characters’ own personal lives, their preexisting conditions. Each storyline ends with a violent cliffhanger or strange event that haunts the next strand and keeps suspense at a fever pitch.

Cregger and cinematographer Larkin Seiple emphasize this internal structure with a visual motif in which the camera follows these characters using long, thoughtfully choreographed shots, such as when Justine enters a liquor store to pick up a couple of bottles of vodka after a tense parent meeting at school.

Sometimes the camera pushes in on the characters threateningly, like an unseen force, or pulls them forward in space, creating a sense of propulsive momentum. As the violence intensifies, Seiple places the camera in surprising places, like when it’s attached to doors that move with the action. The entire film is a masterpiece of camera blocking and long, unyielding shots that wind through the town of Maybrook with these characters.

Both Justine and Archer, at odds with each other initially, find a sense of purpose for their restless energy in investigating the disappearance themselves. Justine follows her one remaining student, Alex, around town, even as she’s painted as a pariah by the parents, and struggles with her own issues surrounding booze and sex.

Archer, a building contractor with an anger problem, decides to problem-solve his son’s disappearance with the tools at his disposal. Neither he nor Justine are entirely trustworthy, but through dogged determination, they find the cracks and chase them down.

Meanwhile, Paul is locked in a game of cat-and-mouse with James, while struggling with his own relationship and sobriety, and James is just trying to score some cash so he can secure his next fix. The kids of this town might have gone missing, but the adults were struggling long before this crisis.

To fully unpack “Weapons” in all of its deliciously creepy and shocking glory would spoil all the fun, and it is best to go in as cold as possible, to allow Cregger’s twisted tale to simply spill over you.

Cregger proves himself to be a master of tone, blending terror and humor masterfully. In casting, he peppers the ensemble with comedy stars in supporting roles, such as June Diane Raphael, Whitmer Thomas and Clayton Farris, who add to the absurd and inexplicable atmosphere. Meanwhile, Abrams might deliver the best and most compellingly authentic performance of the entire company.

With “Weapons” Cregger establishes himself as the foremost purveyor of wicked and witchy contemporary fables that play like demonic urban legends: Did you hear about the Airbnb with the creepy basement? The one about the kids who ran out of their homes in the middle of the night?

What Cregger’s trying to say about the world through “Weapons” — about children, and their relationship with and function to older generations — feels incisive, but never obvious. The ideas here are bigger, and scarier, than just what we experience during the film (which is really very scary).

It’s exciting to see a newer horror voice like Cregger not just maintain his momentum in filmmaking craft but also hit the gas on his ideas. “Weapons” is remarkably captivating because it’s the scariest movie of the year, not just for what happens on screen, but for the larger implications he suggests. It’s the kind of film that leaves the theater with you, whether you want it to or not.

Tribune News Service

(“Weapons” contains strong bloody violence and grisly images, language throughout, some sexual content and drug use) 

‘WEAPONS’

Rated R. At the AMC Boston Common, Causeway, South Bay Center, Alamo Drafthouse Seaport, Landmark Kendall Square, Coolidge Corner and suburban theaters.

Grade: A