Shot in New York in a semi-documentary style, the plot concerns a smallpox outbreak unwittingly imported by diamond smugglers.
The film was based on an article published in Cosmopolitan in 1948 about an actual outbreak of smallpox in New York in 1947.
N.B. – In this 1950 movie, a character mentions that the population of New York City was 8 million.
I assumed it would be much larger now, but not so.