Need advice for a puzzle I'm planning out

I am making a town right now and I had the idea for this building. It's the former mansion of the wealthiest and most influential man in town. He recently went missing despite the fact that he almost never leaves his house. Many men have attempted to enter this house, but none return. This was about five years ago, and so people have learned to not enter. Recently a local tinkerer enters to investigate and he (shockingly) does not come out. The party is asked to go in and try to find everyone.

The twist is: each room is randomized and which room the party enters is determined by my die roll. I want for the party to have to navigate the rooms a specific way in order to find the others who are lost. How can I hint to this without being too specific or too vague? I want for the, "key," to be a note left on the tinkerer's desk somehow.