Poirot is visited by a distraught girl, Norma Restarick, who fears she may have killed someone but runs away, telling him,"You're so old", rather than explaining further. By coincidence, Poirot's friend Ariadne Oliver lives in the same apartment block as Norma and her two room-mates and recently went to their party, where Norma was distressed when she was offered ice-cream. Nor...