An interesting, doubtless unique!, combination of elements in a cleverly wrought story with a neat twist at the end.
Elements include : the American Association of Retired People, Sigmund Freud, antiquities and the need for provenance, Adolf Hitler, and the sfnal element : a machine that can accurately find, and display, memories otherwise long-lost.
The protagonist has a childhood memory of being in Dr Freud’s office, and he is the key to whether there was ever a particular painting on the office wall. Whilst this is the crux of the story to start with, much, much more revealed.