1963. As Professor Mortimer is invited to the USSR by an old archaeologist friend to join in the search for the lost city of Arkaim in the Urals, Captain Blake goes to Switzerland for an important conference between the intelligence services of the Western Powers, in order to prepare for the top-secret Operation Prince in Berlin. Berlin where a West German agent was just shot trying to cross the Wall back from East Germany, uttering a single word before dying: doppelgänger …