In December nineteen hundred, three lighthouse keepers disappeared from Eilean Mor, a remote island in Scotland's Outer Hebrides. When a relief vessel finally reached the lighthouse, the men were gone, yet their daily work appeared to have been completed. ([National Library Board][1])

This episode examines the surviving Northern Lighthouse Board record, the damaged western landing, and the official theory that an enormous wave swept the keepers into the Atlantic. It also separates the documented evidence from dramatic details added by later retellings. ([National Library Board][1])

If the official explanation is probably correct, why has the disappearance of three lighthouse keepers remained a mystery for more than a century?