Plot: Uncovering the secrets of Soviet engineering projects that now lie in ruins; these deserted places are home to extraordinary mysteries and untold secrets, and we revisit them to understand how they were built, and why they were abandoned. This episode is a compilation of segments from S01E03, "Phantoms Of Chernobyl", S01E01, "Nazi Ghost Town", and S01E05, "Soviet Doomsday Device"