In the Western Isles of Scotland, 18 miles from the Isle of Lewis, sits a cluster of smaller islands known as the Flannans.

The largest of the Flannan Islands, Eilean Mor (Big Island in Gaelic), is barely 39 acres in size, rising 288 feet above the stormy North Atlantic Ocean.  It was here that a 74-foot high lighthouse was constructed and lit for the first time on December 7, 1899, flashing twice in rapid succession every 30 seconds to send a send a 140,000 candlepower beam 24 nautical miles out to sea to guide passing vessels safely around Cape Wrath and onward to Pentland Firth.  

On December 15, 1900, just days following the first anniversary of the light being lit for the first time, Captain Holman of the steamer Archtor, bound for Leith, Scotland, noticed the light was out and reported the outage by wireless to the Cosmopolitan Line Steamers headquarters. CLS failed to notify the Northern Lighthouse Board because “other more pressing matters caused it to escape from memory.”

Occasional Keeper Roderick MacKenzie, who was responsible for observing the light from nearby Gallen Head, also failed to notice the outage. Relief keepers due on the island December 20th were delayed by severe storms and did not arrive at the site until December 26th, the day after Christmas. Captain Jim Harvie, noting that the usual relief flag was not flying and the landing was empty, sounded the relief vessel’s whistle and shot a signal flare. Neither of which elicited a response. He then ordered Relief Keeper Joseph Moore to row ashore in the dinghy to investigate.

Landing on the island, Moore found the gate and the outside door to the keepers’ quarters closed. Inside, the kitchen door was open and he noted that the clock had stopped and that the fire was not lit. Finding no trace of the Keepers James Ducat, Thomas Marshall and Donald McArthur, Moore hurried back to the relief boat to notify Captain Harvie, who then ordered four members of his crew to return to the island with Moore to investigate. 

A boat was launched and Joseph Moore was put ashore alone. He found the entrance gate to the compound and main door both closed, the beds unmade and the clock stopped. Returning to the landing stage with this grim news, he then went back up to the lighthouse with the Hesperus's second-mate and a seaman.

A further search revealed that the lamps were cleaned and refilled. A set of oilskins was found, suggesting that one of the keepers had left the lighthouse without them, which was surprising considering the severity of the weather. The only sign of anything amiss in the lighthouse was an overturned chair by the kitchen table. Of the keepers there was no sign, either inside the lighthouse or anywhere on the island.

Moore and three volunteer seamen were left to attend the light and the Hesperus returned to the shore station. Captain Harvie sent a telegram to the  Lighthouse Board dated 26 December 1900, stating:

A dreadful accident has happened at the Flannans. The three keepers, Ducat, Marshall and the Occasional have disappeared from the Island. The clocks were stopped and other signs indicated that the accident must have happened about a week ago. Poor fellows must have been blown over the cliffs or drowned trying to secure a crane or something like that.

The men remaining on the island scoured every corner for clues as to the fate of the keepers. At the east landing everything was intact, but the west landing provided considerable evidence of damage caused by recent storms.

A box at 33 metres (108 ft) above sea level had been broken and its contents strewn about; iron railings were bent over, the iron railway by the path was wrenched out of its concrete, and a rock weighing over a ton had been displaced above that. On top of the cliff at over 60 metres (200 ft) above sea level, the turf had been ripped away over 10 metres (33 ft) from the cliff edge. However, the keepers had kept their log until 9 a.m. on 15 December and this made it clear that the damage had occurred before the writers' disappearance.

The locals learned of the tragedy as the Highland News ran the headline: The Flannan Islands Disaster: A Mystery of the Deep. They were quickly reminded of the previous tragedies to befall on the Flannan Islands in less than a year: one man fell to his death from the lantern gallery and four men drowned when their boat overturned approaching the landing at Eilean Mor. Yet over a hundred years later, the mystery still remains as to what happened to the Flannan Islands keepers. 

Ducat had not wanted to be stationed at Eilean Mor. He may have had a premonition about the place. He had appealed to Robert Muirhead, superintendent of the Northern Lighthouse Board, saying that it was not the most suitable place for a man with a young family. Muirhead insisted, however, saying that he wanted a reliable, experienced and conscientious crew to man the new station and he wanted Ducat, with his 21 years in the service, to be the principal keeper. Thomas Marshall was appointed 2nd Assistant and William Ross was named 1st Assistant. During the first year, however, Ross became ill and Donald McArthur, an occasional keeper, was sent to replace him. 

To a lone keeper, the solitary life can be peaceful and idyllic but Ducat, Marshall and McArthur did not experience an idyllic life on Eilean Mor. To survive, they were required to raise and slaughter their own sheep and poultry, grow their own vegetables and catch their own fish. They had minimal contact with the mainland. Also, with three men confined to small quarters for lengthy periods personalities can clash and even turn deadly. When their disappearance was discovered, a new crew was assigned and the investigation continued. With one chair found overturned, the kitchen door left open and a set of rain gear left behind. It appeared that the last person had left the quarters in a hurry.

Why then would that person take the time to close the outside door as well as the gate? Principal Ducat’s log was current up to December 13th, with details for the 14th written in chalk on a slate. He had noted weather conditions, state of the light, supplies and barometric and thermometer readings.

He had also entered the time of extinguishing the light on the dawn of December 15th and wind direction at 9:00 a.m. Therefore, the light had been turned off on the morning of the 15th and had not been turned back on that evening when the Architor passed. 

Michael Joseph, a researcher investigating the mystery noted that: “... the morning’s routine duties had been performed subsequent to that hour. The big lamps in the lantern-tower had been trimmed in readiness for another night’s vigil: the canteens and oil fountains were primed: the lens and mechanism had been cleaned and polished in the usual way after a night’s revolving. All this took time. Furthermore, everything in the kitchen was in order. Utensils used in the preparation and consumption of that morning’s breakfast were all clean and in their place. This seems to add to the conviction that doom befell the keepers in the late forenoon, before lunch time."

On December 29th, Superintendent Muirhead arrived on the scene accompanied by two experienced keepers. They concluded that it was probably McArthur who left in a hurry, knocking over the chair. They surmised that Ducat and Marshall had gone out to check the security of the equipment at the west landing leaving McArthur in the quarters to deal with the chores. They further speculated that from his vantage point, McArthur observed a series of exceptional waves approaching and dashed out to warn Ducat and Marshall. When he reached them it was too late and all three men were washed out to sea. 

Researcher Richard Wilson disputed this theory. He noted: “Considering the rule that a lighthouse should not be left unmanned, all three men would not be out at the same time unless the last man was called to some dire emergency. But if such an emergency had indeed been discovered at the west landing, how could the last man, occasional keeper Donald McArthur, have been summoned to it?

Neither visual signal nor cried-out sound would have reached him: the west landing was too far away and obscured from sight. Yet the fact that the kitchen chair was toppled and that McArthur’s coat and Wellingtons’ were left behind suggests that he did indeed make a dash outdoors, in his shirt-sleeves, into a freezing December day. But if he were in such a hurry, why did he then bother to shut the doors and the gates behind him?“

Historically, the Flannan Islands had been marked by superstition from the time they were named for the obscure Saint Flan. Prayers were supposedly said by all who set foot on them.

It was also said that the “Phantoms of the Seven Hunters” so resented the intrusion of the lighthouse that he lured the men over the cliff to their death. In any event, another 70 years passed without further incident and in 1971, the light was modernized and automated, making Keepers unnecessary.

The lonely Flannan Island Light continues to scan the ocean, probably looking for a trace of its long-lost keepers.