In Vivarium, a young couple gets sucked into a 21st-century suburban nightmare, a neighborhood filled with an endless sprawl of homes of the exact same size and shape, cutting them off from the outside world and crushing them under the weight of the cruel sameness of their surroundings.
Unlike the ordinary suburban nightmare of the twenty-first century, the pair is enslaved by extraterrestrial humanoids and must watch as one of their types develops from infancy to adulthood inhumanely quickly.
Tom (Jesse Eisenberg) and Gemma (Imogen Poots) are kidnapped by Twilight Zone-style monsters who promise to “free” them once their charge reaches adulthood and lead them through a maze of mint green cookie-cutter cottages.
Tom and Gemma, unable to accept their fate, plunge into their respective types of madness, leading to a kaleidoscopic voyage through several dimensions and a climactic moment that is both mysterious and violent.
In the last twenty minutes, Gemma, desperate to know where her horrible adoptee goes every day and who he’s meeting in their deserted suburban wilderness, slips after him underneath a portion of the pulled-up sidewalk and finds herself tumbling through various colored pocket universes, each inhabited by other sets of despairing, unwilling “parents” to identically dressed, little black-haired boys.
Many have given up, committed suicide, or just sit at their kitchen tables looking. She is thrown back to her own world, where she can only watch in horror as her charge “releases” Tom’s corpse, placing him in a body bag and putting him into the grave he dug compulsively during his final days.
When Gemma is eventually “released,” too, their “boy,” who is now more of a man, fills up the car with gas, drives himself out of the housing development, and returns to the foreboding real estate agency, where he takes up his elderly coworker’s post, donning the nametag and waiting for an unsuspecting couple to walk through his doors.
What occurs is quite simple to grasp, but you need to go all the way back to the start if you want to figure out why it occurs and where you can find a very scary clue.
The film opens with shots of a nest containing what appear to be tiny young birds, except for one that isn’t. After accidentally knocking over an egg and then one of its fellow birdlings and dragging it to the ground, the parents focus all of their attention on the enormous baby, who turns out to be a young cuckoo, and it quickly becomes too big for the nest to contain it.
It is well-known that many cuckoo species are brood parasites, meaning that the parents don’t provide any real care for the young. Instead, they place their egg in another bird’s nest, and their young swiftly assume leadership of the family after hatching.
A lot of adoptive families break up because one of the kids has such a huge appetite that it drives the parents crazy, and they end up dying.
Whatever the creatures of Vivarium are, they share a common trait: they rely on humans for everything from food to supervision. While their origins, motivations, and ultimate goals beyond procreation are never revealed, the impression is left that they have been exploiting humanity’s prowess in childrearing for some time.
Gemma tells one of her preschool kids, “That’s how it is,” when it questions the evilness of the cuckoo’s life cycle.
The Boy disappears into Yonder near the end of Vivarium and later reappears with a symbol-filled book.
Gemma, desperate to find a way out, plays a game with The Boy in the hopes that he will divulge his whereabouts, only for The Boy to start transforming into a monstrosity. The boy’s rapid maturation into an adult is reminiscent of a scene from a John Carpenter sci-fi film.
Tom continues to spend all day digging his hole, and The Boy eventually locks his “parents” out of the house. Gemma’s attempts to track him down on a daily basis come to naught. Eventually, a body in a body bag is unearthed in Tom’s hole.
His own condition deteriorates swiftly, and he passes away while under Gemma’s care. When The Boy finally returns to them with a corpse bag after telling them it’s time to “free” him, they know exactly what he means.
Frustrated by shock and revulsion, Gemma swings at him with a pickaxe, but he ducks beneath the surface, lifting the asphalt like a rug and sliding into a subterranean world reminiscent of Escher’s art.
Following along, Gemma learns that Vivarium’s Yonder is stuffed to the brim with limitless parallel universes where couples like her and Tom are trapped in identical situations. It’s become abundantly evident that the extraterrestrial invasion known as Vivarium uses human couples as experimental subjects in a gruesome experiment.
They’re all depressed, some to the point of considering suicide. After being vacuum-packed in a corpse bag and spit back into her world, Gemma meets her end at The Boy’s hands.
He disposes of the bodies by placing them in the hole Tom excavated, which he then backs up, and then he leaves Yonder to go back to the real estate business. Martin is elderly and nearing the end of his life there (though only a year has passed).
He gives The Boy his name tag and then dies, making way for a new Martin to take his place. A new set of buyers and sellers enters the real estate office, and the process starts all over again.