When in 1908 the young British historian G. M. Trevelyan was in Sicily collecting information for his trilogy of books on Garibaldi and the campaign for Italian unification, he decided to follow on foot the journey of Garibaldi and his "Thousand" in 1860 from Marsala to Palermo, crossing some of the most desolate parts of the island. His parents were worried that he might be kidnapped and held to ransom, since he was known to come from a well-off family. Trevelyan wrote to explain that Sicily wasn't particularly dangerous these days, and furthermore he was intending to take with him three friends from Cambridge - one of whom was Bertrand Russell!
I have always thought this would be the most unforgettable of holidays: a walk across Sicily with Bertrand Russell and G. M. Trevelyan; both at the time young men at the height of their powers. Alternatively, can we imagine Bertrand Russell kidnapped by Mafiosi, and the dialogue that might then follow? But I am not certain that the trip ever took place, since Russell makes no mention of it in his autobiography.
Incidentally, Trevelyan never mentions the Mafia in his Garibaldi books, though he is aware of the Camorra, the equivalent organised crime organisation in Naples. This perhaps supports the theory that, although banditry has been endemic in Sicily for countless centuries, the Mafia as we know it today is actually a relatively recent creation.
(I would recommend to anyone Trevelyan's trilogy: "Garibaldi's Defence of the Roman Republic", "Garibaldi and the Thousand" and "Garibaldi and the Unification of Italy". They are a model of how history should be written for the general reader.)