Ottessa Moshfegh has built a cult following thanks to her depiction of unlikeable, irredeemable characters, particularly women. From an heiress who sedates herself for a year to avoid trauma in My Year of Rest and Relaxation, to a septuagenarian dreaming up scenarios at turns both violent and erotic in Death in Her Hands.

In her fifth novel, Moshfegh takes her formula of depravity and perversion into the Dark Ages, fleshing out a gory pseudo-parable about what happens to a person raised in hardship and despair when the wheel of fortune turns in their favour.

Set in a fictional medieval serfdom ruled over by the childish Lord Villiam and his right hand man Father Barnabas, Lapvona is populated by a poverty-stricken and God-fearing cast of characters who work to appease their rarely seen ruler and protect the village from bandits.

Once a prosperous land, Lapvona is weakened by numerous attacks, secretly organised by William to keep villagers subservient. Shielded in his castle high on a hill, Villiam is ignorant of the lives of his villagers, instead believing that everything that happens is a performance put on to entertain him.

Despite Moshfegh's arresting prose, which zeroes in on details of village life such as the eyelashes of dead bandits brushing off the sheets that cover them, not much is told to the reader about this era or setting, which is clearly the author’s intent.

Because of this, though, it’s hard to resist the mental image of Shrek’s Lord Farquad and the simplistic caricature of medieval life.

What sets the world apart, of course, is its deep depravity, which is evoked so vividly at times that it’s hard to shake the feeling of misery.

At the core of the story is 13-year-old Marek and his lamb herder father Jude, who is related to Villiam through a shared great-grandfather. The pair live a life of hardship, marked by intense manual labour and Jude’s violent outbursts.

Marek, born with a "spine twisted in the middle so that the right side of his rib cage protruded from his torso", is presented as a sensitive but pathetic character, a "stray dog" that craves approval. He welcomes his father’s beatings, believing that "God [will] love him more through pity".

Jude, meanwhile, is a "bachelor" during a time when, Moshfegh writes, men took their "young cousins" for wives if they needed one. Caught up in his fury at having to raise Marek, after his mother fled after his birth, Jude radiates anger "like vapour".

Still, he has moments of tenderness. After watching a bandit be hanged and gutted, Jude suggests to Marek that they pick flowers on the way home. Jude himself has moments of peace and appreciation in nature, believing the "kiss of sun" to be God. He obsessively dotes on his lambs, cooing over them until he has to send them to slaughter, after which he is bereft.

These moments, however, are like trap doors laid by Moshfegh, only serving to make the oncoming acts of violence all the more unsettling.

Their lives radically shift when Marek kills Villiam’s spoilt son and heir Jacob, prompting the lord to demand an exchange – his dead son for Jude’s living one – catapulting Marek into a life of ease and into the unnerving role of entertaining Villiam.

Enhancing the fairy tale motif is Ina, the village witch who acts as the linchpin for the novel, a mystical figure who survived a plague during her youth and nursed herself back to health by drinking her own breastmilk. She is the unofficial wet nurse of Lapvona, suckling its inhabitants and providing cures.

Here is where the plot sadly dries up. Plunged into a drought that sees the rivers run dry, crops fail and livestock die, the villagers are plagued by "suicides, madness, [and] blasphemy". At the same time, the reader learns that Villiam is hoarding water in a hidden reservoir, where he takes frequent naked dips with Father Barnabas.

The villagers finally turn to cannibalism, throwing off their religious abstention from eating meat in order to survive. Reading it feels like staring into a petri dish, as all morality and codes of behaviour are thrown out.

The depravity climaxes with a ghoulish case of mistaken identity that wouldn’t be out of place in a Monty Python film, and a rape that may or may not have been a dream.

However, no major storyline surfaces. Instead the reader watches as more seasons pass in Lapvona, as the rains return, crops begin to thrive and Villiam contends with his mortality. Here, Moshfegh lets fall some of the props in her medieval farce, as distinctly millennial concerns and experiences start plaguing the characters.

Villiam suffers a ludicrous crisis of self and imposter syndrome brought on by his assumed role as the next father of the son of God, while Marek becomes more like a typical apathetic and whiny teenager, blind to the luxury that once dazzled him. He doesn’t self-actualise once he rises up out of poverty or escapes abuse. He drowns his sorrows in wine on Christmas Day and plunges deeper into cynicism.

When the novel builds to its bleak conclusion, there are no thrilling acts of bravery or redemption, or even a moral to the parable. But this, of course, is how Moshfegh wants it. "Right or wrong, you will think what you need to think so that you can get by", she writes. "So find some reason here."

Lapvonia is published by Jonathan Cape