Deep in the Belgian Congo in 1939, white missionary nurse Angie Dickinson--a virtuous woman who carries the Holy Bible like a shield--arrives in a small village just as the resident doctor dies of a heart attack. The natives believe this is the curse of their wrathful god who lives in the mountains, so it's up to Dickinson's Rachel Cade to teach them the word of Christ as well as earn their trust under her (limited) medical supervision. It would be easy for cynics to dismiss this adaptation of Charles Mercer's novel "Rachel Cade" as Hollywood hokum, but the conviction with which it is presented doesn't feel plastic. Dickinson's prayers for a new doctor are answered in the arrival of an RAF pilot (Roger Moore, with not one hair out of place); however, his attraction to her isn't romantic, rather lustful--desires which go against everything she stands for. The plot is soapy, certainly, and Peter Finch has the thankless role of an agnostic colonel who makes big entrances and exits yet seems pretty inefficient. The religious aspect is handled sensitively, while the "Sin" of the title refers to a personal shame which was a very real concern for single women in the early 1940s. Beautiful Warner Bros. production includes impressive J. Peverell Marley cinematography. **1/2 from ****