Nobody in film has yet portrayed evil bitch, and sometimes crazy evil bitch, as well and as often as the late great Bette Davis, as evidenced by such films as "Of Human Bondage", "Whatever Happened To Baby Jane", and "The Nanny", just to name a few that come immediately to mind. Capable of spitting out lines such as "Ah'd luv tuh kiss yuh, but ah jus' washed mah hair" (from "Cabin In the Cotton", 1932), "Every time you kissed me, I had to wipe my mouth! Wipe my mouth!" (from "Of Human Bondage", 1934) to "But Blanche, yuh ahhh in that chair, yuh ahhhhhhh!" (from "Whatever Happened To Baby Jane", 1962), Bette Davis made a lucrative living with her hip-swinging sashaying stride and her mannerisms that still make her a favorite of drag queens everywhere.
In "Dead Ringer", Bette was once again cast in the dual role of good sister/bad sister (Edith Phillips/Margaret DeLorca) similar to her dual roles in "A Stolen Life" (1946, with Glenn Ford). Paul Henreid, her co-star in "Now Voyager" - remember him in the classic scene that involved his lighting two cigarettes and handing Davis's character one of them - directs. "Dead Ringer"'s premise is simple: good sister impulsively tries to step into shoes of deceased bad sister in an ill-conceived move to improve her own quality of life, without thinking of the inherent consequences. In this case, as in the case of "A Stolen Life", Davis inherits the dead bad sister's myriad mix of self-imposed problems, but with worse consequences.
And as veteran filmgoers have realized for many years, the family dog always knows who's who.
Karl Malden, as Davis' earnest boyfriend (and cop) Sgt. Jim Hobbson is basically re-enacting his earnest boyfriend characterization from "A Streetcar Named Desire", and Peter Lawford, who was a real-life playboy and drunk, (in addition to allegedly acting as a bit of a pimp for the Kennedys, circa the Marilyn Monroe/John F. Kennedy/Robert Kennedy liasons era), plays Tony Collins...the drunken playboy boyfriend of the dead bad sister, Margaret DeLorca.
"Dead Ringer" was made in an era of more rudimentary special effects, so Davis's two characters interacting almost face-to-face in some scenes was quite innovative for the time, well-done (better than the obvious stand-in used for some scenes) and still holds up well.
Fun times ensue for all. Classic Bette melodrama.