Don't worry. She's not essential to my plan.
3 seconds sound clip from the Back to the Future Part II movie soundboard.
You can hear this line at 00:05:50.484 in the Blu-ray version of the movie.
Quote context
[...]
- Relax, Marty. It's just a sleep-inducing alpha rhythm generator.
- She was asking too many questions, and no one should know too much about their future.
- This way, when she wakes up, she'll think it was all a dream.
- Then what did you bring her for?
- Don't worry. She's not essential to my plan.
- First, you've gotta get out and change clothes.
- Right now? It's pouring rain.
[...]