Joe Rose has planned a postcard-perfect afternoon in the English countryside to celebrate his lover's return after six weeks in the States. To complete the picture, there's even a "helium balloon drifting dreamily across the wooded valley." But as Joe and Clarissa watch the balloon touch down, their idyll comes to an abrupt end. The pilot catches his leg in the anchor rope, while the only passenger, a boy, is too scared to jump down. As the wind whips into action, Joe and four other men rush to secure the basket. Mother Nature, however, isn't feeling very maternal. "A mighty fist socked the balloon in two rapid blows, one-two, the second more vicious than the first," and at once the rescuers are airborne. Joe manages to drop to the ground, as do most of his companions, but one man is lifted sky-high, only to fall to his death.
             In itself, the accident would change the survivors' lives, filling them with an uneasy combination of shame, happiness, and endless self-reproach. (In one of the novel's many ironies, the balloon eventually lands safely, the boy unscathed.) But fate has far more unpleasant things in store for Joe. Meeting the eye of fellow rescuer Jed Parry, for example, turns out to be a very bad move. For Jed is instantly obsessed, making the first of many calls to Joe and Clarissa's London flat that very night. Soon he's openly shadowing Joe and writing him endless letters. (One insane epistle begins, "I feel happiness running through me like an electrical current. I close my eyes and see you as you were last night in the rain, across the road from me, with the unspoken love between us as strong as steel cable.") Worst of all, Jed's version of love comes to seem a distortion of Joe's feelings for Clarissa.
             Apart from the incessant stalking, it is the conditionals--the contingencies--that most frustrate Joe, a scientific journalist. If only he and Clarissa had gone straight home from the airport... If only the wind hadn...