 The plot calls for a man (Daniel Gélin (qv) in the role of Louis  Bernard) to be discovered as "not Moroccan" because he was wearing  black makeup. The makeup artists couldnt find a black substance  that would come off easily, and so they painted the fingers of the  other man (Jimmy Stewart (I) (qv)) white, so that he would leave  pale streaks on the other mans skin (according to  Patricia Hitchcock (qv), this idea was suggested by Daniel Gélin).