In the first sentence of Feebleminded, the world is experienced as a kind of “horizontal vertigo”. It’s a pretty good description of what reading this slim book is like: an intense, disturbing, accelerating spiral. Originally published in Spanish in 2015 as La débil mental, it is the second part of what the Argentinian author Ariana Harwicz has termed an “involuntary trilogy” exploring extreme mother-child relationships. Her previous book, Die, My Love (translated by Carolina Orloff and Sarah Moses), was narrated by a young mother driven to the edge of madness by desire, loneliness and frustration. Its stream-of-consciousness style and the visceral intensity of its prose – uncomfortable, but completely engrossing – earned it a place on the Man Booker International prize longlist last year.