The Killer That Stalked New York (1950)

Arriving at New York City's Pennsylvania Station after a trip to Cuba, Sheila Bennet (Evelyn Keyes), who is smuggling $50,000 worth of diamonds into the country, realizes she's being followed by the authorities. She mails the diamonds to her husband, Matt Krane (Charles Korvin), instead of carrying them around, and then tries to shake the Treasury agent following her.

Feeling sick, Sheila nearly faints on the street, so a cop takes her to a local clinic. While there, she encounters a little girl and inadvertently infects her. Sheila is misdiagnosed as having a common cold, and she leaves and returns home. After the girl is admitted to the hospital, she is found to have smallpox.

Meanwhile, Matt has been cheating on Sheila with her sister, Francie (Lola Albright), and then attempts to take off without either of them when the diamonds finally arrive through the mail. Unfortunately for him, the fence cannot buy the diamonds because they are too hot. Matt will have to wait for ten days for the cash, so he cannot leave New York. Sheila confronts Francie, who kills herself afterward due to Matt's betrayal of them both. This gives Sheila more reason to get revenge on him.

Finding a growing number of smallpox victims, city officials decide to vaccinate everyone in New York to prevent an epidemic, but quickly run out of serum. This causes a panic in the city. Tracking the victims, agents realize that the disease carrier and the diamond smuggler are one and the same. However, an increasingly sick Sheila continues to elude capture. Still unaware that she has smallpox, she returns to the doctor at the clinic to get more medicine. The doctor explains her illness and tries to talk her into turning herself in, but she shoots him in the shoulder and escapes.

Sheila eventually catches up with Matt, who tries to escape from the police, but falls from a building ledge to his death. Sheila nearly attempts to drop herself from the ledge, until the doctor tells her the little girl she met had died. Remorseful, Sheila turns herself in and, before succumbing to the disease, provides authorities with a badly needed list of those she contacted.