I've gone to that place where there were some people being sacrificed. I released them and some head priest ran down some stairs under the alter to a secret library.
There is a locked up room in the middle where I assume the priest is hiding. I've found three switches on the walls, but hitting them, in any order, doesn't open up the sealed room. I assume there is another switch or I'm missing something else.
The switches I've found are two on some corners in the North and NW, and then another against the SE wall of the sealed room.
Would love some help here as I can't find clues anywhere.
Thanks.