06 May, 1882, the Number One administrator of the British government in Ireland and his Number Two are assassinated by men wielding deadly surgical knives while the pair are walking in the Phoenix Park. The killings are witnessed from the Viceregal Lodge, now Aras an Uachtarain, the official residence of her majesty's representative in Ireland.One of the dead men is Lord Frederick Cavendish - who is married to the niece of the prime minister, William Ewart Gladstone. The other man is Thomas Henry Burke, the head of the Irish Civil Service, a man denounced by Nationalists as the leading 'Castle Rat' in the British 'occupation'.The British government must solve this crime. But there are no clues. The witness descriptions are inconclusive and the local police do not know where to begin...