It began, as the best stories do, with no plan at all. A rainy afternoon in Florence, a bookshop neither of them had meant to enter, and two people reaching for the same shelf at exactly the wrong — or perhaps perfectly right — moment.

Sophia was searching for Calvino. James had given up looking for anything in particular. They argued, politely at first, about which edition was superior. By the time the rain had stopped, they had exchanged numbers and discovered they lived four streets apart in London.

Two years later, standing on that same cobblestone street — he had kept the address, she had kept the book — James asked a question he had been carrying for months. She answered before he finished the sentence.