The serum that private nurse is using in her hypodermic needle... I heard the doctor tell her that an overdose would be fatal.
11 seconds sound clip from the Attack of the 50 Foot Woman (1958) movie soundboard.
You can hear this line at 00:35:33 in the Blu-ray version of the movie.
Quote context
[...]
- Our necks are way out if Nancy comes to and talks.
- There is a way out, if you've got the nerve.
- Try me.
- Money certainly brings out the best in you, doesn't it?
- Slide over and drive to town. I've got things to do.
- Aah! Doctor! Dr. Cushing! Something's happened to Mrs. Archer! Aah! Aah!
[...]