London police superintendent Thomas Pitt is assigned to attend a secret conference on self-government for Ireland, in order to prevent possible clashes between the so-called “implacable friends”—Irish Catholics and Protestants. According to the official protocol, Thomas’s wife, Charlotte, goes with him as well—especially since the meeting has been arranged at Ashwood Hall, a country house belonging to Charlotte’s younger sister. But Thomas doesn’t succeed. The already difficult negotiations are shattered by the tragic death of Greville, the intermediary between Irish factions. Little by little, Thomas and Charlotte come to the inevitable conclusion: the killer could not have entered the house from the outside. That means he is one of those present—and he is still in the house. Which means the minister’s death may not be the last…