Under Capricorn is overlong and talky, with scant measure of the Alfred Hitchcock thriller tricks.
Time of the plot is 1831, in Sydney, NSW, during that period when a convict, after serving his time, could start life anew with a clean slate. Such a man is Joseph Cotten, former groom and now Ingrid Bergman’s husband. Cotten has become a man of wealth, but is not accepted socially.
That fact, along with his past crime – the killing of his wife’s brother, a deed committed by Bergman but for which he took the blame – are the motives stressed as causing the wife’s addiction to the bottle.