Dee Wallace, LAOH National Irish Historian, shared this book on Irish-American history: Patrick Campbell’s A Molly Maguire Story, available on Amazon.
In the coal mining regions of Pennsylvania’s Schuylkill County between 1861 and 1875, a series of violent attacks, arsons, and murders were attributed to the Molly Maguires. The Mollies originated in 1840’s  County Donegal, Ireland, an offshoot of other secret societies such as the Whiteboys and the Ribbonmen in response to harsh treatment from landlords and horrible working conditions.
According to local authorities in Schuylkill County, the local Molly Maguires were responsible for the attacks. They executed ten Irish-American immigrants on 21 June 1877, including Patrick Campbell’s great uncle. An additional ten Irish-Americans were executed over the next 18 months.
Patrick heard of his great uncle’s execution while living in County Donegal and began his investigation while living in New Jersey in the 1970’s. His book is the story of his investigation.
Sources: Amazon blurb for A Molly Macguire Story; History Channel – Who were the Molly Maguires