This film by underrated director John Brahm is one of the more interesting works of the 1940s (not one of the best, but different).
Laraine Day plays Nancy, about to marry and hiding some dark secrets in her past. She was excellent at this kind of thing. Gene Raymond (not the most charismatic of actors but surprisingly good here) plays her intended, with Brian Aherne as the psychiatrist who knows about her previous life.
In flashback we see Nancy and her husband (a young Robert Mitchum) and then into another flashback (daring to attempt this at the time when many films were still pursuing conventional structure).
'The Locket' of the title obviously holds the key to the mystery, and we have an absorbing time pulling all the loose ends together. Reginald Denny, Ricardo Cortez, and Ellen Corby decorate an accomplished cast.