As the film opens, two thugs kill another thug. When the body is discovered and about to be autopsied, the doctor realizes that although the man was shot dead, he was also suffering from the Pneumonic plague--a very nasty and more virulent version of the Bubonic plague! So, it's a race against time to find those who came in contact with the dead man and treat them immediately, otherwise a disaster could erupt.<br /><br />Oddly, I actually know quite a bit about the Pneumonic plague, as I taught a series of lectures on it for my history classes. The film really did not do a good job of getting the facts right about the disease in that it looked little like what the people had in the movie. The biggest problem is that this illness is so incredibly grotesque that in 1950 they really wouldn't have been allowed to show it. Sure, there is high fever and coughing (they got this right) but also lots of bleeding and explosive vomiting of blackened blood--along with the enormously swollen lymph nodes like you'd get with the Bubonic plague--all purply and gross! I can certainly understand why they didn't go this far. Also, I am sure that the federal government would have had a much, much greater involvement in controlling and treating the disease--here in the film it was handled on a very local level and everyone seemed ill-prepared and a bit dumb. No one seemed willing to believe the doctors!! As for the acting, the film had some excellent actors here. Richard Widmark and Paul Douglas are, respectively, the public health doctor and police chief. Good actors but also known actors back in 1950. However, in his first film is the very menacing Jack Palance (still going by his original moniker, 'Walter Jack Palance') as well as the relatively unknown (at the time) Zero Mostel. Palance was great--very scary and very physically adept in his own stunts. Mostel played a heavy typical of his early work--a greasy and cowardly sort of evil.<br /><br />Overall, despite really not getting the details right and wrapping everything up a little too neatly, the film is very tense and has excellent acting--and is well worth seeing.