Home to one of the most remote lighthouses in the United Kingdom, the Flannan Isles have signalled danger to shipping in the Atlantic for over 100 years. But for a week in December 1900, no signal came from the Flannans. When a ship was sent to investigate, the crew found the lighthouse empty, the three lighthouse keepers had disappeared and were never found. But it's said that three huge black birds patrol the island, as they have done since that stormy Christmas in 1900!