Julian Treslove, a professionally unspectacular and disappointed BBC worker, and Sam Finkler, a popular Jewish philosopher, writer and television personality, are old school friends. Despite a prickly relationship and very different lives, they've never quite lost touch with each other - or with their former teacher, Libor Sevick, a Czechoslovakian always more concerned with the wider world than with exam results.
Now, both Libor and Finkler are recently widowed, and with Treslove, his chequered and unsuccessful record with women rendering him an honorary third widower, they dine at Libor's grand, central London apartment.
It's a sweetly painful evening of reminiscence in which all three remove themselves to a time before they had loved and lost; a time before they had fathered children, before the devastation of separations, before they had prized anything greatly enough to fear the loss of it. Better, perhaps, to go through life without knowing happiness at all because that way you had less to mourn? Treslove finds he has tears enough for the unbearable sadness of both his friends' losses.
And it's that very evening, at exactly 11:30pm, as Treslove hesitates a moment outside the window of the oldest violin dealer in the country as he walks home, that he is attacked. After this, his whole sense of who and what he is will slowly and ineluctably change.