This week marks the 20th anniversary of the signing of the Good Friday Agreement, the peace deal that ended 30 years of sectarian conflict in Northern Ireland. The agreement between the British and Irish governments, and the main political parties of Northern Ireland, remains a benchmark for countries across the world seeking to end civil wars. In a period of turmoil across the Middle East and Asia, it also serves as a valuable lesson that groups considered “terrorists” often end up being negotiated with. “A Secret History of the IRA,” by Irish journalist Ed Moloney, is a stunning piece of journalism that looks in detail at the lives of some of the IRA’s leading members and examines how and why they were finally persuaded to make peace. Among the book’s many remarkable chapters is a section looking at the tragic case of Jean McConville, a mother of 10 who became one of the “disappeared” when she was kidnapped and shot dead by the group in 1972.