Whispering City's locale is Quebec City, that odd European fortress set high over the St. Lawrence River; it comes to Gallic life more fully here than in Alfred Hitchcock's I Confess, made a few years later.
The death in an auto accident of a long-retired actress spurs crime reporter Mary Anderson to work up a feature story; the woman was sent to a sanitarium years before for insisting that her fiance's death was actually murder. Pursuing a lead, Anderson interviews a prosperous benefactor of the arts (Paul Lukas), who seems curiously bothered by the visit. Currently, Lukas serves as the patron of an impoverished young pianist/composer (Helmut Dantine; the two actors both appeared in Watch on the Rhine). Dantine is working on something called The Quebec Concerto; an oddly scored work, its orchestra features a Sousaphone rearing its brassy bell.
An overcomplicated but still compelling plot involves Dantine's disturbed shrew of a wife, who's dependent on injections to make her sleep; the discovery of her suicide, which is made to look like murder (well, it seemed to work once); a blackmail scheme to engineer another murder; and a faked death made to look like yet another murder. (Eagle-Lion was not known for the elegant simplicity of its plots.)
Oddly, it all works, if a bit creakily. Mary Anderson suggests two-thirds Teresa Wright and a third Bonita Granville; the latter impression no doubt derives from her sleuthing around in a jaunty tam, like Nancy Drew. She has the distinction (as does the director, the short-lived Fedor Ozep, as he's credited here) of helping to make the best Nancy Drew mystery ever released. That's faint praise, but praise nonetheless.