Mysterium: Secrets & Lies consists of six new characters; six new locations; six new items; and 18 story cards. This latter group of cards can replace the object cards in the game; with each card representing one way in which the ghost died. Now instead of trying to get each investigator to identify an object — a singular item that wouldn't have much nuance to it — the ghost must instead use the dream cards to convey the story of their demise; something far more challenging.