The Man with a Cloak (movie, 1951)

Set in 19th-century New York, this mystery begins when a Frenchwoman shows up at the home of one of Napoleon's former marshals. The alcoholic man is badly crippled and slowly dying, but this doesn't stop the forthright lady from pushing him to change his will to include his estranged grandson so that he can help out the struggling French Republic. Unfortunately, the dying man's conniving housekeeper and butler, already planning murder to get the money themselves, overhear her and begin plotting her demise.