From time to time I skim the front-page of games workshop's main vendor website and was delighted to see a new book from one of my favourite science fiction authors Adrian Tchaikovsky for a Warhammer 40K IP. When I was reading Children of Time, I was impressed how the author was able to describe the whole evolution, cultural struggles and even the communication of a spider species. The new book's cover revealed that the plot would cover the viewpoint of the genestealer cults.
The Warhammer fandom wiki defines them as “A Genestealer Cult is a xenos-worshipping secret society made up of and controlled by Tyranid Genestealers that thrives in the dark corners of the Imperial underworld across the galaxy.”. Basically, someone got infected by aliens, had children which themselves had also children and over time these humans transform to so called "Tyranids". If there is a critical mass of them in this genestealer cult they rise up and take over a planet so it can be consumed by a hive fleet.
Yes you have read correctly they are being consumed by their kin to serve as bio-mass for even greater monsters. The whole book's plot can be summarized by this sentence: "An end in horror is better than horror without an end.". The protagonist is the champion for one of these genestealer cults that does not believe in the message of the cult and is offered salvation by monsters or to live under monsters for eternity. The book overs a good amount of twist and turns, so expect to be surprised.