In stories, especially creepypasta, its sounds more like a magical contract than a piece of paper
Like if a private organisation hired you to kill people, a NDA doesn’t somehow make that legal and you can’t get sued for breaking the contract.
So, what is the legal extent of NDA?
I work for a company that uses NDAs, though I am not under one. Some of the things covered are our designs, our suppliers, and the names of our customers.