In 1856, at the tender age of 24, Henry Plummer became the marshal of Nevada City, Calif. Within three years, he was serving 10 years in San Quentin for murdering the husband of a woman with whom he was having an affair.
Released after six months, he joined a gang of stagecoach robbers before forming his own gang and terrorizing gold-mining camps across California and Montana.
After losing a sheriff election in 1863 and running off the winner, Plummer pinned on the badge. Thereafter, under the guise of cracking down on crime, Plummer and his gang of toughs, known as the Innocents, hanged witnesses to a skyrocketing number of crimes: murders, robberies, assaults, and sundry other illegal goings-on.
On January 10, 1864, having had enough law enforcement for a while, fifty to seventy-five vigilantes rounded up Plummer and his two deputies and hanged them in the basement of a Bannack, Montana, store.