On the morning of June 28, 1914, when Archduke Franz Ferdinand and his wife, Sophie Chotek, arrived at Sarajevo railway station, Europe was at peace. Thirty-seven days later, it was at war. The conflict that resulted would kill more than fifteen million people, destroy three empires, and permanently alter world history.

reveals in gripping detail how the crisis leading to World War I unfolded. Drawing on fresh sources, it traces the paths to war in a minute-...