Books are the best companions in the world

I’m about a third of the way through my 26-week book challenge (well, okay, a little further than that), and I’ve just realised that I should have done another interlude after my Fifty Shades rant. If people recall, that covered my most overrated book, so it makes sense for the original challenge to also ask for my most underrated book. And this is a question I cannot answer.