I'm always iffy about David Mitchell's stories. 'Cloud Atlas' (2004) and 'The Bone Clocks' (2014) did nothing for me, neither did 'The Thousand Autumns of Jacob de Zoet' (2010). Randomly grabbed a book and ran out of the flat. When I looked at it later, groaned when I realized it was 'Slade House' (2015). Okay fine. Let's try this. (Reviews here, here, here, and here.)
'Slade House' (2015) is meant to be a companion to 'The Bone Clocks' (2014). You could google the storyline. If you have read his earlier works, then you'd realize that he's creating a world, and the references in this book hark back at those. It mentions Doctor Iris Marinus-Fenby, who is known as Marinus the Horologist. This character appeared in as a male in 'The Bone Clocks' and is also a key character in 'The Thousand Autumns of Jacob de Zoet'. The author must really like this immortal. In this book, the immortal character is female. Also, soul carnivores. You know this one really well. Soul carnivores are central to this book that spans a time frame of four decades from 1979 to 2015.
Set in London, we have twins Norah and Jonah Grayer, who are soul carnivores. They live in Slade House, home to the Grayer family. The twins were born in the 1800s and in 1930s, hid away in Slade House, placing the estate in a bubble and isolating it from Time itself. They entrap humans with psychic abilities (latent or otherwise), kill them and feed off their souls. They are then embroiled in a fight with Marinus (as a woman this time) who is here to investigate the deaths of all these humans over the decades.
Oddly, I really don't mind this book. I like the plot and flow much much better than the other works, even though it takes many references from the worlds that the author has previously created.
The woman is not here by chance: her appearance is caused by the Script. Dusk hauls me to itself, but now I perceive an alternative fate, I resist. My newborn mission makes me strong, and my mission is this: one day, however distant, I will whisper into Marinus's ear, 'You killed my brother Jonah Grayer - and I kill you now and for all time.' I transverse down with the ponderous snow, the living snow, the eternal snow; undetected, I pass through the mother's coat, her underclothes, her skin, her uterus wall; and I'm home again, my new, warm home, my anchorage; immune to the Dusk and safe in the brain of a foetal boy, this miniature, drowsing, curled-up, dreaming, thumb-sucking astronaut.