The Mysterium: Secrets & Lies consists of 6 new characters, 6 new locations, 6 new items, and 18 story cards. This last group of cards can replace the object cards in the game, with each card representing a way in which the ghost died. Now, instead of each investigator trying to identify an object - a unique object that wouldn't make much sense - the ghost must instead use dream cards to convey the story of their death, something much more difficult.