The Cold War, with its architecture of state against state, bloc against bloc, ideology against ideology, has given way to a new basket of conflict-bearing impulses: nationalism, ethnic tension, and irredentism. The last occupies these authors, particularly the question of when irredentism -- that is, the claim on land controlled by others based on one's nation's ties to that land -- leads to costly actions, even war, and when it does not. Armenia, Croatia, and Serbia fall into the first category; Hungary, Romania, and Russia, the second. Consider the Sherlock Holmes metaphor of dogs that do not bark: comparing those that do and those that do not in the case of irredentism is rather rare, and Saideman and Ayres go about the task with carefully specified hypotheses linked to deductive arguments tracing back to dominant international relations theories. Out of this array, they privilege the impact of domestic politics over more popular explanations that feature international factors, for example, the restraining influence of institutions such as the European Union. When plumbing the force of domestic politics, they consider the material, self-regarding calculations of political leaders alongside the variable character of nationalism. The weak irredentism of Russia's case, for example, they attribute principally to the amorphous state of Russian nationalism and the lethargy among ethnic Russians abroad.