A cluster of military defensive structures among a quaint holiday village lie deserted on a San Francisco Bay island; experts investigate and uncover a mysterious Civil War outpost that conceals a dark and hellish history... Stories: 1) Camp Reynolds, Angel Island, California; 2) Aqueduct of Padre Tembleque, Hidalgo State, Mexico; 3) Nant-y-Gro Dam, Elan Valley, Wales; 4) Babruysk Fortress, Babruysk, Belarus