There is a pentagram with five candles in Olmstein's room. The goal is to lit up all the candles.
After interacting with one of the candles you get a message: "Know this seeker. Books hold untold meaning. Order is capital."
This is the low-spoiler guide for "The pentagram" puzzle in Gibbous - A Cthulhu Adventure. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.