Ali Smith's new novel is a meditation on a world filling up with borders, on what richness and worth are, on what harvest means. From Shakespearian jeu d'esprit, via Keatsian melancholy and the sheer energy of 1960s Pop Art, this first in a quartet of novels casts an eye over our own time, asking who we are, where we are, right now. Here is time, ever-changing, ever cyclical. Here comes Autumn.