On December 26, 1900, the relief ship Hesperus arrived at the remote Flannan Isles to a chilling scene: the lighthouse was deserted, and its three keepers — Thomas Marshall, James Ducat, and Donald McArthur — had vanished without a trace. Cryptic log entries, puzzling clues, and a century of speculation have fueled theories ranging from rogue waves and foul play to the supernatural. Dive into one of maritime history's most haunting unsolved mysteries and uncover the enduring enigma of the Flannan Isles lighthouse keepers.