It's actually of interest to compare this film to Psycho, I think, in how it's so akin to to how Hitchcock tells the story of the ordinary people of the world getting involved with a certifiable gentlemen. Things start to unravel, however, when two detectives on his trail come into town, bringing to young Charlie to light what could be going down, or what might not be, or what is as clear as psychopathic day.
The oldest daughter, also named Charlie (Teresa Wright), almost feels like a kindred spirit to her uncle, happy as can be that he's come to visit. The whole concept to the story is very appealing- a (painfully) normal suburban family gets a calling from a relative- Uncle Charlie (Joseph Cotten)- who wants to come by for a little while. True, it doesn't go for the immense macabre that lay in Psycho, The Birds, and Frenzy, but it is very effective in telling its stories, and giving us character to either love, or love to hate. One thing that strikes many who come upon Shadow of a Doubt, one of this filmmaker's triumphs, is the knowledge that it was Hitchcock's favorite among his own films- and many watch it with very high expectations, getting shot down as well, making it one of his more under-rated efforts.