One day, during the British run of Copenhagen, winner of the Tony Award for best play in 1999, Frayn was presented with a curious package from a London housewife that contained a few faded pages of barely legible German. These pages, apparently found concealed beneath some floorboards, seemed to cast a remarkable new light on the mystery at the heart of the play. While Frayn began to lose all sense of certainty, actor David Burke, who played Niels Bohr in the London production and had some experience with documents of this sort, followed the action with particularly close interest....