“Midnight Special” is a cryptic and suspenseful sci-fi road picture, a thriller so tightly pitched it would work even without the magical science fiction element.

Writer-director Jeff Nichols has done some of his best work with children (“Mud”) and Michael Shannon (“Take Shelter,” “Shotgun Stories”), and here, he recasts the veteran movie heavy as a boy’s hero. Possibly.

Because we aren’t told who he is or why he and another rough-looking character (Joel Edgerton) are dashing through Texas in the dark with a child (Jaeden Lieberher) who is the subject of an Amber Alert.

The kid’s wearing ear protection. He’s got tinted swim goggles on. And he’s reading comic books.

“What’s Kryptonite?”

The men bicker over how to answer that.

“He needs to know what’s real,” Roy (Shannon) gripes.

Turns out, they’ve kidnapped the boy from The Ranch, a Branch Davidian style cult, one led by Sam Shepard. Turns out, Lucas (Edgerton) has some skill in making their getaway. He wears night-vision goggles and races toward the state line with the lights on their primer-covered early ’70s Chevelle turned off. Nothing suspicious about that.

They stop each dawn, taping up the windows of every cheap motel room, keeping out the light. Evenb the peephole is covered in duct tape.

The Fed (Adam Driver) questioning the cult leader seems to have a lot of information about the boy, this Alton Meyer. The preacher (Shepard) and his followers seem pretty straightforward with their answers. That kid is “special.”

“Y’all have no clue what you’re dealin’ with, do you?”

Nichols taps into movie history, with touches of “Sugarland Express,” “Close Encounters,””E.T.” and most pointedly, “Starman,” for this harrowing pursuit picture.

There’s a date and a location, a deadline racing toward them. The Feds, with Driver in the classic Jeff Goldblum (semi-comical science questioner/science explainer) role, are trying to catch them.

And the cult, benign as it might seem, would like the boy back.

“Midnight Special” doesn’t over-explain, doesn’t spoon-feed us the particulars. It relies on those earlier films and our collective filmed science fiction memory to backfill much of the story. We see mass arrests, possibly sinister government overreach, Texas (gun loving) cults, a “chosen one” child, military base interrogations that ask too many of the right questions to not suggest that somebody outside of the assorted getaway cars this trio uses has an idea of what they’re looking for and why.

Shannon wears his menacing baggage, but suggests a soft side with Roy, something he rarely gets to play. Edgerton mimics Shannon’s quiet drawling growl for this film, further connecting the characters and reinforcing the sense that they have history — geographical history. Young Mr. Lieberher (“St. Vincent”) nicely suggests a small child with a calling. He strikes one purposeful pose after another as Alton starts to participate in his own kidnapping or escape, depending on how you look at it.

Kirsten Dunst shows up later as the child’s world-weary/cult-weary mother, a marvelously earthy turn.

As I said, the road picture/getaway elements of “Midnight Special” are so tense and so engrossing that the sci-fi could be excised from it without hurting the film. But it makes for a dazzling upping of the ante, right up to the film’s finale.

That’s where Nichols’ sense of how much to show, how much to explain, fails him. Like another low-budget sci-fi picture, the more comical “Safety Not Guaranteed,” this one blows its effects budget in a finale that spoils the mystery and fails to do what it is plainly set up to do — overwhelm us.

But “Midnight Special” still makes for a creepy peek into the world of cults, of those who escape them (safe houses), of a government that knows more than it should and still doesn’t have “the answers.” And it’s an absolutely chilling road picture, filled with tension, dread and a threat of violence. The longer we don’t know where that threat is coming from, the more suspenseful it is.

MPAA Rating:PG-13 for some violence and action

Cast: Michael Shannon, Joel Edgerton, Kirsten Dunst, Adam Driver, Jaeden Lieberher, Sam Shepard
Credits: Written and directed by Jeff Nichols. A Warner Brothers release.

Running time: 1:52