In 1978, Adam Nicolson received three Hebridean islands as a 21st birthday present from his father, Nigel. The Shiants, each about a mile long, were uninhabited, with just one rat-infested bothy: not everyone’s idea of paradise. But, precisely because human beings had neglected them, wild life flourished — the islands were ‘thick with the swirl of existence’, thrumming with life and death, suffering and triumph, ferocity and conquest.