> There's not an option to search the person I tied up in the storeroom.

The body search bit comes a bit later!
I assume you've taken care of your would-be torturer?
In one of the rooms it says something about timings for your jailers - that's quite important!
When outside the building, use the listen option, to guide when you should throw the rock.
(Here's a quote to guide you on your way = "If a tree falls in a forest and there's no-one to hear it; does it make a sound?")
If one direction doesn't work try another.
Good luck
Kediri :o)