Host Robert Stack presides over an investigation into unsolved mysteries ranging from murders to UFO sightings. Through reenactments and interviews, viewers are presented with the known facts of each case. Anyone with additional information is then urged to contact the show's producers via a toll-free telephone number.
Bylo to na kanálech:
Ctihodný občan 
Ordinace v růžové zahradě 2 
Mission: Impossible 
