The unreliable narrator kind of became its own genre briefly - Gone Girl, Girl on a Train, Silent Patient - I hated all of them. As a reader it is super easy for the writer to just flat out lie to me, and then create this big shocking twist that everything I’ve been reading is a lie. It strikes me as lazy writing.
That said, the Silent Patient is even worse than that, because the lies were to poorly constructed that I picked the murder on page 9. Literally. As I was just starting the book, I said to my wife “if the killer turns out to be so and so, this book will suck.” And suck it did.
Every book is under 100 pages, you just might need a really small font and a magnifying glass to read it.
But to be serious, Heart of Darkness (77 pages). That is a dense book.