Woman trapped with a gorilla. What movie was it?

I remember seeing a movie as a little kid with my dad and his side of the family. He didn't really care that I was just a kid, he would put on whatever he wanted and if I had to watch, so be it. So I ended up seeing the Matrix in the theater at only 5 years old.

This movie I watched was some kind of adventure movie from the 80s or 90s. At the beginning there was a scene with a woman trapped in a dungeon or cage with a pissed off gorilla and she was screaming and crying, pointing a gun at it. As the movie went on, there was an old man who was part of the story, and he turned out to be the villain or something and at the climax he turned into some weird robed "being."

I don't know what this film was, but if someone could help me identify it I would be really grateful!

EDIT: There was only a gorilla at the beginning of the movie. The movie wasn't about a gorilla. I believe it was some kind of adventure movie or something.