Born into an established Ulster family just a fortnight after the death of Parnell and dying in the year following the outbreak of the modern 'Troubles' in Northern Ireland, O'Shiel was in many ways atypical of the Irish nationalists of his day.

Election agent for Arthur Griffith in the Cavan by-elections and a friend of Michael Collins, he was to sit as the first judge in the Dáil courts. He held various offices from January 1922, including assistant legal advisor to the Provisional and first FS government and director of North Eastern Boundary Bureau. He was also Chair of the Garda Commission Report, and prepared Ireland's case for admission to the League of Nations. From 1923 to 1963 he served as an Irish Land Commissioner.

Richly illustrated, the book draws on substantial archival research, including its subject's extensive unpublished memoirs, shining a light on O'Shiel's life and career and offering a rare insight into middle-class Ulster Catholic nationalist culture in the late 19th- and 20th centuries.