A brilliant child tries to keep herself fed and her paralyzed father alive in the mesmerizing science fiction drama “Vesper.” It’s about biological collapse and biological rebirth on an Earth even more starkly-divided into “haves” and “haven’t a prayers.”

That’s the source of her name, the evening prayer that Vesper (Raffiella Chapman) represents. As in a lot of science fiction, she offers a glimpse of hope in the grimmest of futures

The world-building in this tale by Lithuanian horror/sci-fi filmmakers Kristina Buozyte and Bruno Samper (“Vanishing Waves”) is next-level dystopian and just gorgeous to behold. Earth has entered “The New Dark Ages” thanks to environmental collapse exacerbated by bio-genetic tinkering and the oligarchical transfer of wealth. Most biodiversity is gone in a rain-soaked landscape of dead or dying forests and swamps teaming with synthetic biological creatures — tentacled blood-sucking fungi, armor-piercing bugs and blind, bird-headed snakes that pop out like deep ocean eels to peck and poke at whatever passes by.

But Vesper prowls this wasteland like a child who grew up with it and who regards it with a scientist’s eye, perhaps thanks to instruction from her bedbound father (Richard Brake). Darius can’t move and doesn’t speak except through the hovering drone that accompanies Vesper everywhere.

Some wag has given the talking drone a “Wilson” face. Yes, some Tom Hanks movies will survive the Apocalypse.

Her father’s life support is bacterial powered, everyone’s starvation diet is heavy on exotic worms and Vesper is studying and experimenting with both in her lab. She wants to create seeds that will give her bargaining chips to get her and Dad into The Citadel.

The superrich haven’t flown off to Mars. They’ve built bubble cities with controlled air and armed protection and synthetic companions called Jugs. The wastelands are peopled by few, but along with the masked, faceless “Pilgrim” scavengers, there are those who do business with the rich. Jonas (Eddie Marsan) is a figure straight out of Dickens. He “cares” for a teeming group of children who act as his gang, and whose blood he sells to The Citadel who use it for heaven knows what.

Then Vesper stumbles across one of the beautiful people of The Citadel whose Wing Glider crashes and the balance of this world changes. She nurses Camellia (Rosy McEwen) back to life, and what they learn about each other could alter lives, the balance of power and the future.

There are traces of the post-nuclear “Threads” and the tubular, liquid tech of “Brazil” in this understated thriller. The visuals are often stunning, with lots of attention paid to creating the biology of a world where science tried several Hail Mary attempts to bring flora back to a fauna-less landscape. Many of these plans are more fauna than flora and the CGI that renders them is stunning.

The disembodied voice of Brake as Darius brings a wary weariness to the advice he tries to pass on to his child.

“You don’t know the cost of dreams.”

Marsan delivers his distinct brand of disarming menace to this Fagin figure, comforting kids as he exploits them, complimenting Vesper as he threatens her.

Young Miss Chapman is given an androgynous look that suits the material, and the character and her performance of her have just the right hint of pluck. McEwen, of TV’s “The Alienist,” has a “Man Who Fell to Earth” ethereal quality in this guise — fragile and worried and lost.

The story’s arc may feel familiar, but it isn’t utterly predictable, with the child’s enterprise and cunning nicely matched against Marsan’s I’m Bigger Than You omnipotence. And the messaging of “Vesper” leaves this bleak tale a little room to breathe and anyone watching it the tiniest prayer of hope.

Rating: unrated, violence

Cast: Raffiella Chapman, Rosy McEwen, Richard Brake and Eddie Marsan.

Credits: Directed by Kristina Buozyte and Bruno Samper, scripted by Kristina Buozyte, Brian Clark and Bruno Samper. An IFC release.

Running time: 1:53