There were seven attempts to assassinate Queen Victoria during her long reign; four of them were of Irish origin. The most serious of all was the Jubilee Plot, a conspiracy apparently hatched in New York by the Fenian Brotherhood to blow up the Queen, her family and most of the British Cabinet with dynamite at the great service of thanksgiving to commemorate the 50th anniversary of her accession, held at Westminster Abbey in June 1887. The plot was uncovered by Scotland Yard with just a few days to go. Several of the bombers were caught, tried and sentenced to penal servitude for life. But - warned off in time - the master bomber escaped to America. Using declassified Foreign Office secret files, the author discloses the secret at the heart of the British counter-intelligence operation against militant Irish nationalists: the entire conspiracy was masterminded for its own reasons by a clandestine British agency reporting directly to the Prime Minister, Lord Salisbury.