Fassbender. Knightley. Mortensen. Meet the red-hot cast of A Dangerous Method, David Cronenberg’s unblinking biopic of Freud, Jung and the messy birth of psychoanalysis. Warning: contains spanking…

Lake Constance, Bodensee, Austria. 21 July, 8am.

David Cronenberg sits hunch-shouldered over a monitor in baseball cap, blue jeans, trainers and zipped-up windbreaker. Twenty paces in front of him, stood beside the vast mercury lake, stands Keira Knightley, her elegant features and swan-like neck appearing quite at home in this rarefied, recreated world of horse-drawn carriages, sailboats, straw hats, waistcoats, floor-length dresses, ribbons and parasols

She gazes out across  the water as Michael Fassbender, sat on the edge of a white boat with a red sail, drifts ever closer. Cronenberg’s regular DoP Peter Suschitzky closes steadily in on Knightley’s thoughtful face to capture Fassbender’s POV. Three takes and then a change of set up allows us to witness the action from Keira’s view, the camera hanging on her shoulder and holding the shot for two whole minutes as the sailboat breezes in.

“Cut,” says Cronenberg, clear and soft. Suschitzky good-naturedly grumbles, “It’s an impossible shot. Water moves, that’s the nature of it…” and a speedboat whizzes to the shore to fuss over Fassbender. Then a diver pops up, clinging to the side of the sailboat boat. Ah, the magic of movies…