Vertigo - Carlotta's Necklace
After Judy's transformation she and Scottie decide to eat out - she fancies Ernie's but he suggests they head out of town. She becomes increasingly nervous as the miles rack up ... what she doesn't know is that when she had changed to go out Scottie had recognized her necklace as matching the one that Carlotta wore in the portrait (see that earlier post here). He now knows that she had been impersonating Madeleine and tells her "there's one final thing I have to do, and then I'll be free of the past".
Then ... We see them on the same stretch of road as earlier when Scottie had driven Madeleine to the mission at San Juan Bautista (see that here).
... and Now, the same view, looking south down Highway 101 just south of the 156 East turn-off to San Juan Bautista.
Then ... He arrives at the San Juan Bautista mission and drags her towards the bell tower. By now she knows he's on to her and, scared, tries to resist, but to no avail.
... and Now, this footage was filmed on a studio sound stage but the mockup was closely based on the real cloisters, seen below in this recent photo.
Scottie knows that if he makes it to the top of the tower (he had failed the first time and watched helplessly as Madeleine fell to her death) then his vertigo affliction will be cured. In an incredibly dramatic denouement he forces Judy up the vertiginous stairs (also filmed on a studio set), getting her to confess on the way. They make it to the top where, as she clings to him, professing her love, she sees something move. A step backwards, a scream, and she is gone.
It was a just a nun who had followed them. The movie ends with Scottie staring down in disbelief at the loss, for the second time, of his beloved Madeleine.