‘You understand, Lenú, what happens to people: we have too much stuff inside and it swells us, breaks us.’ The line comes from the third of Elena Ferrante’s Neapolitan novels, but it offers a fair summary of a sequence that concludes in this fourth volume. Set in Italy between the 1950s and the present, and documenting the turbulent friendship between two women from the same working-class quarter of Naples, these books by a still-unidentified pseudonymous writer rattle like pressure-cookers with anger, outrage, frustration, jealousy and spleen.