This film was based on a Henry James novel called The Aspern Papers. Restyling it as The Lost Moment probably had something to do with them changing the name of the integral character from Aspern to Ashton. I can't help thinking that the novel title is a more intriguing one than The Lost Moment though.
Publisher Lewis Venable (Robert Cummings) travels to Venice in search of the love letters of the poet Jeffrey Ashton. Ashton disappeared years earlier quite suddenly and the last place he was seen was this house. His lover, Juliana Borderau (Agnes Moorehead), still survives at the age of 105 and lives in the house with her niece, Tina (Susan Hayward). Venable takes a false name and takes rooms in the house but it soon becomes clear that getting the letters will be hampered by the fact that Tina displays a remarkable tendency to take on her aunt's life, putting them all in danger.
This film worked well on several levels. It was atmospheric with some good performances from the leading players. However, I felt it lost some of its plot tension halfway through, as the mystery of Tina has already been revealed and the secondary concern - what happened to Ashton - has been mentioned so little as to drive it from the mind. The second half of the film is a psychological exploration as Venable tries to make sense of Tina and then cure her.
There are some truly good scenes, such as the one where we finally see the withered face of Juliana and the explosive finale, but in others the narrative descends into melodrama. Words that wouldn't seem preposterous on the page sound bizarre coming from the mouths of actors. The original text was quite short and, after seeing this, I'm keen to read it to find out how much of his characters James actually put across and how much was artistic licence on the part of the producers.