The trick to flying safe, Zoë always said, was never to buy a discount ticket and to tell yourself you had nothing to live for anyway, so that when the plane crashed it was no big deal. Then, when it didn’t crash, when you had succeeded in keeping it aloft with your own worthlessness, all you had to do was stagger off, locate your luggage, and, by the time a cab arrived, come up with a persuasive reason to go on living.