Standing, like strange echoes of each other, at the beginning and end of Sarah Hall’s short-story collection Madame Zero are two deeply disconcerting tales. Told from the perspective of a husband, both these stories describe apparently contented – if not perfect – marriages that go unexpectedly, shockingly awry. In ‘Mrs Fox’ (winner of the 2013 BBC National Short Story Award), a woman, Sophia, ‘dreams subterranean dreams, of forests, dark corridors and burrows, roots and earth’. Sophia is ‘in part unknowable’ to her husband. One day, he wakes up in their modern town house to find his wife vomiting; the next day, he hears, from the bathroom, ‘the low cry of someone expressing injury, a burn, or a cut, a cry like a bird, but wider of throat’. They go for a walk on the heath and, as the woods thicken, Sophia begins to walk ‘strangely’. She runs, she crouches. As her husband catches her up, he notices that ‘something is wrong’. She turns and runs; then she stops and he is ‘struck dumb’: Sophia has been transformed into a vixen.