This excellent revival - 11 years after an Auckland Theatre Company production - is stupendous intellectual stimulation, wonderfully presented and unapologetically wordy.
Like Tom Stoppard's tragi-comedy Arcadia, Michael Frayn's remarkable drama is a melange of physics, philosophy and history, brimming with ideas and the connections between them.
It centres on a real-life mystery: why did Werner Heisenberg - head of a German nuclear programme and Niels Bohr's erstwhile protege - visit Bohr and his wife, Margrethe, in Nazi-occupied Copenhagen in 1941?
As unreliable memory and anger throw up different answers and deeper questions, Frayn intriguingly delves into the social psychology of scientists, the ethics of the Bomb and mid-war life in central Europe. (Heisenberg says puddles of phosphorescence burning in Allied-bombed German cities are hard to keep off his shoes: "As if the streets have been fouled by the hounds of hell.")
Scientific explanations abound - atoms are snowflakes and fission bombs are avalanches - but Frayn is subtle enough not to let any metaphors solidify into heavy-handedness.
