There were many animals there in cages. They were put through the most unspeakable tortures to satisfy some scientific curiosity.
14 seconds sound clip from the The Secret of NIMH (1982) movie soundboard.
You can hear this line at 00:51:40.735 in the Blu-ray version of the movie.
Quote context
[...]
- Why did he never tell me about any of you? Why?
- To answer that, I must tell you about NIMH and our plan.
- We were captured, put in cages, and sent to a place called NIMH.
- Often, at night, I would hear them crying out in anguish.
- 20 rats and 11 mice were given injections.
- Then, one night, I looked upon the words under the cage door and understood them.
[...]