Journey to Outcast Island

On a desolate island near Greece, abandoned buildings are evidence of a group of people that were forbidden to leave; experts reveal who was forced to stay here and if there was a cover-up to conceal what really happened at this strange place.
Stories:
1) Isle of Portland, UK;
2) Pratt Cotton Gin Factory, Alabama, USA;
3) Spinalonga Leper Colony, Crete, Greece