There is something cruelly beautiful, delightfully frustrating and filthily gorgeous about a Scarlett Thomas novel. Two family trees open and close this book: one shows what the characters think they are and how they are related, the other what they are revealed to be. How the couplings shift is less important than the chains of desire that cannot be mapped or taxonomised.

The Gardener family is reeling from and sneakily plotting about the death of great-aunt Oleander, owner of Namaste House, a retreat for whack jobs and slebby failures. But her will leaves them confounded. This family of botanists are each given a seed which might flourish into death or enlightenment. It might explain their genealogy, and the deaths of four of their forebears. So too might a magical book, which changes according to who is reading it — which, when you think about it, is a description of every book. Thomas’s gift is to make the obvious awfully surprising.

‘What the deuce,’ Sir Walter Scott once wrote ‘is a plot for but to bring in good things?’ So this unconventional Aga-saga includes an anorexic tennis player, an obese and alcoholic estate agent whose only joy is unnecessary purchases, a drab academic worried about his lack of publication, a newspaper columnist so trendy he’s tepid, a documentary filmmaker obsessed with the fact that trees can walk and a Christian Grey of plant sciences, wondering about whether or not cavemen invented dildos. Miraculously, it all hangs together. The connective tissue is Thomas’s whip-sharp, snarky wit throughout. She is the laureate of the sardonic and the sarcastic. Imagine Muriel Spark’s disreputable niece, punky and porny and puncturing every balloon of ego. The novel is outré and extravagant, unremitting and unrepentant, sweet and sour and salty.

This is a novel to read for its riffs rather than its arc. Thomas fulminates throughout — diets, protocols in universities, anthropomorphism, the etiquette of sado-masochism, fashion, pick-your-own vegetables and childlessness are all subjected to her fierce glare. She has developed a tendency to use capitals, in a similarly choleric style to the equally angry novels of Lucy Ellmann. With the point of view ricocheting between different characters, Thomas allows herself daring little cadenzas — such as the chapters in the voice of a bird, who is markedly more like James Joyce than Henry James. The prose is both lithe and livid, describing a world where even lettuces are obsessed with sex and violence. The satire is so exuberant and the ideas so quick-fire that the catastrophic closure is genuinely shocking. Late on, we understand that we actually care about these narcissistic, silly, dislikeable, unfortunate meatbags. That is no small achievement, a kind of forceful empathy.

The Seed Collectors confirms Thomas as one of the most startling, unpredictable writers of her generation. As with books by Nicola Barker or Lauren Beukes, you cannot guess the ending from the outset; Thomas will take you on a frolic all of her own. This is a clever, chaotic novel, with a steely edge hidden behind its rambunctious shenanigans.