The play examines the moment when a previously strong friendship was rendered untenable. In 1941 Heisenberg visits Bohr and, after a quiet talk, Bohr is so angered that they are never able to repair their relationship. Indeed, the meeting that takes place in the play is only possible once all three characters are dead; only death allows them to critically reexamine the moment when their friendship could no longer endure.

There are many examples of how the friendship between Bohr and Heisenberg is tested throughout the play. The very fact that a German scientist under Gestapo supervision is visiting a half-Jewish scientist in an occupied country raises suspicion. Bohr and Margrethe discuss the difficult position Heisenberg has put them in: They will be viewed suspiciously by the SS and treated as collaborators by their fellow Danes. Simply by visiting the house, Heisenberg is endangering the friendship and testing the boundaries of what it can endure.

He finds the limits of this endurance during the private meeting between the two men, when he asks Bohr whether physicists have “the moral right to work on the practical exploitation of atomic energy” (25). The question has so much subtext that it infuriates Bohr, who cuts their meeting short.