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 they must decipher to help the ghost remember how he was murdered; Who did the crime? Where did it take place? Which weapon caused the death? The more the mediums cooperate and guess well, the easier it is to catch the right culprit.