DISAPPEARANCE: Lighthouse Keepers At Flannan Isles Lighthouse (Season 3 Ep. 5)

In December of 1900, three lighthouse keepers mysteriously disappeared.  James Ducat, Thomas Marshall and Donald McArthur were supposedly to be at the lighthouse when a relief boat arrived to bring supplies, but they were gone, the island still and empty.

Thought there had been signs of a storm, the fate of the three lighthouse keepers has been debated endlessly and what happened to them remains unknown.