So some square dance googling let me to this:

Lang’s last film of the forties was a neo-Gothic that may have been inspired by Hitchcock’s Suspicion and Rebecca. Secret Beyond the Door (1948) involves a vacationing heiress who meets and marries a charming stranger; they return to his mansion, in which each room has been decorated identically to the site of a famous murder. A follow-up film, House by the River (1950), concerns a writer who murders a servant girl. There was a lot thrown into the mix-sexuality, ghosts, square dancing (!) — and homicidal frenzy triggered by perfume. (In Secret Beyond the Door the killer scent was lilac.) Though the film was reckoned a failure, it did offer a villain Lang would return to again, the corrupt writer.

Square dancing? I can’t really tell which movie contains the square dancing, but I searched on both, and couldn’t find any further reference to square dancing…although I did find out that Alfafa was in House by the River.