Elias's already-reclusive behaviour became even more bizarre; he would either lock himself in his room and drink heavily, or rush about the grounds in a frenzy while carrying a pistol.

Joseph took possession of the estate and examined the room, finding scattered records of Elias's time in the United States.

The only clue he can provide is a page from Elias's diary, dated March 1869 and detailing that pips were sent to three men; two were later "cleared" and one was "visited."

After John departs, Holmes deduces that Elias had returned to England and gone into hiding because something in the United States had prompted him to flee for his life, and that the letters were sent from a sailing ship based on their postmarks and the time lapse between the first two mailings and the recipients' deaths.

as the Ku Klux Klan, an anti-Reconstruction group in the South that was active until its sudden collapse in 1869 – triggered, Holmes theorises, by Elias's return to England with vital records that the other members have since been trying to recover.

The next morning's newspaper carries an article on the discovery of John's body in the River Thames, apparently the result of an accidental drowning after falling off the Waterloo Bridge.

Now convinced that all three Openshaw men were murdered, Holmes spends the day checking the records of sailing ships and finds only one that could have been in Pondicherry, Dundee, and London when the letters were mailed – an American barque, the Lone Star.

He also sends a telegram to the Savannah police, informing them that the captain and mates – the only American crewmen – are wanted in England for murder.

At the time of writing, the actual Ku Klux Klan was indeed broken and effectively defunct, and it would be decades before its 20th century revival.

Conan Doyle's taking it up in this story was in line with his recurrent theme of wild and violent Americans and other foreigners exporting their power struggles to Victorian Britain – which already formed the basis to A Study in Scarlet, the very first Holmes mystery.

[13] The third episode of the 2010 BBC Sherlock series titled "The Great Game" made reference to five pips being sent by an assassin organization as a warning.

The Sherlock 2016 Special "The Abominable Bride" also refers to the original short story, as a murder victim is mailed five orange pips as a threat before being killed.