Every student needs a certificate saying he is no communist

In 1961 a student strike paralysed the school system in Haiti. Francois Duvalier answered by dismembering the students' association. One of the measures he imposed required each student to produce a police certificate attesting that he belonged to no communist group or association suspected by the state, along with a certificate of good conduct from the civil court. The courts issuing those papers were staffed with the president's own supporters. Duvalier added that a parent would be held responsible if a child was absent from school without a doctor's note. He had already used the Cold War to pass anticommunist laws banning most civic organisations and political parties, and a series of American governments backed those laws, which became the legal base of a family dictatorship lasting twenty nine years. Students, union members and party leaders left the country in numbers to avoid arrest and torture, and many of them landed in New York.

Islam is old in Africa and its place in government has been argued over since independence. South of the Sahara the argument has mostly concerned the standing of Muslims inside states with large Christian populations. Nigeria applies sharia in the northern states while national politics turns on how Muslims and Christians divide the presidency and the ministries. Islam there is local and adapted, with sufi orders predominating, which is precisely what campaigners for a pure orthodoxy attack. Where Muslims are a minority, as in Kenya and Tanzania, they have organised as a lobby around economic neglect. North of the Sahara it went differently. Sadat was killed in 1981 by Islamists who regarded his agreement with Israel as a betrayal, and Mubarak inherited the fight with the Muslim Brotherhood. In Algeria the Islamic Salvation Front took on the FLN and the country fell into civil war in the early 1990s. War between the north and south of Sudan ran from 1955 with one interval and had left about 1.5 million people dead by 2002.

In January 1965 Diederich met Greene at the airport in Santo Domingo and set out before dawn with the exiled priest Jean-Claude Bajeux in a chartreuse Volkswagen Beetle to drive the length of the Dominican side of the border. Their cover was that they were checking Dominican jails for missing Haitians. Bajeux was six months from the disappearance of his own family. Diederich's purpose was to get Greene close enough to Haiti to write about it, since Greene could not return. Greene later wrote in the American edition of his novel that the best he could do in January 1965 was to make that trip along the border in the company of two exiles and pass along the edge of a country they loved. The final chapter of the book, in which the guerrillas cross into the Dominican Republic, comes directly out of those three days.

Under Francois Duvalier, president of Haiti from 1957 to 1971, the men who worked for him carried the bodies of their victims out to Titayen, a stretch of desert ground at the foot of the coastal mountains a few miles from Port-au-Prince, and left them there for crows, goats and vultures. Everyone understood the choice of ground. Haitians who serve the spirits hold that a permanent link runs between a person's spirit and the physical remains, which is why tombs are built above ground with flat roofs that work as tables for offerings of food and rum on birthdays, on All Saints' Day and on the first of January, which is Ancestors Day and Independence Day at once. To withhold the body was to cancel all of that for the whole family. The name of Titayen stayed in the national memory, and in 2010 whoever picked the site of the mass graves for earthquake victims picked the same ground.