On Chesil Beach by Ian McEwan

"Suddenly a North Oxford boy whose name she had forgotten, a gaunt, twenty-two-year-old boy with glasses, came out of the darkness and trapped her. Without preamble, he began to outline for her the consequences of a single hydrogen bomb falling on Oxford. Almost a decade ago, when they were both thirteen, he had invited her to his home in Park Town, only three streets away, to admire a new invention, a television set, the first she had ever seen. On a small, grey, cloudy screen framed by carved mahogany doors, a man in a dinner jacket sat at a desk in what looked like a blizzard. Florence thought it was a ridiculous contraption without a future, but forever after, this boy-John? David? Michael?- seemed to believe she owed him her friendship, and here he was again, still calling in the debt."