Mysterium In the 1920s, Mr. MacDowell, a gifted astrologer, immediately detected a supernatural being upon entering his new house in Scotland. He gathered eminent mediums of his time for an extraordinary séance, and they have seven hours to make contact with the ghost and investigate any clues that it can provide to unlock an old mystery.Unable to talk, the amnesiac ghost communicates with the mediums through visions, which are represented in the game by illustrated cards.