At the date of Plummer's arrival in the mining country, the town of Lewiston, Idaho, was the emporium of a wide region then embraced under the name of Idaho Territory; the latter also including Montana at that time. Where his life had been spent previous to that is not known, but it is thought that he came over from California. Plummer set up as a gambler, and this gave him the key to the brotherhood of the bad. Gamblers usually stick together pretty closely, and institute a sort of free-masonry of their own; so that Plummer was not long in finding, among men of his own profession and their associates, a number of others whom he considered safe to take into his confidence. Every man accepted by Plummer was a murderer. He would have no weaklings. No one can tell how many victims his associates had had before they went into his alliance; but it is sure that novices in man-killing were not desired, nor any who had not been proved of nerve. Plummer soon had so many men that he set up a rendezvous at points on all the trails leading out from Lewiston to such mines as were producing any gold. One robbery followed another, until the band threw off all restraint and ran the towns as they liked, paying for what they took when they felt like it, and laughing at the protests of the minority of the population, which was placed in the hard strait of being in that country and unable to get out without being robbed. It was the intention to seize the property of every man who was there and who was not accepted as a member of the gang. One killing after another occurred on the trails, and man after man was lost and never traced. Assaults were made upon many men who escaped, but no criminal could be located, and, indeed, there was no law by which any of them could be brought to book. The express riders were fired upon and robbed and the pack trains looted. No man expected to cross the mountain trails without meeting some of the robbers, and, when he did meet them, he expected to be killed if he made resistance, for they outnumbered the parties they attacked in nearly all instances. The outlaws were now indeed about three times as numerous as those not in sympathy with them. Rendered desperate by this state of affairs, a few resolute citizens who wanted law and order found each other out at last and organized into a vigilance committee, remembering the success of the Vigilantes of California, whose work was still recent history. Plummer himself was among the first to join this embryonic vigilante movement, as was the case in so many other similar movements in other parts of the West, where the criminal joined the law-loving in order to find out what the latter intended to do. His address was such as to disarm completely all suspicion, and he had full knowledge of facts which enabled him to murder for vengeance as well as for gain.