Shadow of a Taxman investigates how the unrecognised Irish Republic's money was solicited, collected, transmitted, and safeguarded, as well as who the financial backers were and what might have influenced their decision to contribute. The Republic's quest for funds took its emissaries as far afield as New York, Buenos Aires, Cape Town, and Melbourne, as well as virtually every parish in Ireland. By selling 'war bonds' to supporters, it raised £370,165 from 140,000 people in Ireland and nearly $6m from 300,000 people in the United States. These bonds promised a return to subscribers when British forces had left Ireland and an independent Irish Republic was internationally recognised.

Exploiting newly uncovered documents, Shadow of a Taxman reveals the identities of these subscribers. Cross-referencing with census returns, intelligence reports, memoirs, and IRA membership rolls, it provides the first demographic analysis of non-combatant supporters of Irish independence on the eve of its realisation. It also shows how access to funds shaped the course of the Irish War of Independence and, ultimately, Irish republicans' negotiating position with the British government in 1921.