Face-to-face diplomacy has long been the lynchpin of world politics, yet it is largely dismissed by scholars of International Relations as unimportant. Marcus Holmes argues that dismissing this type of diplomacy is in stark contrast to what leaders and policy makers deem as essential and that this view is rooted in a particular set of assumptions that see an individual's intentions as fundamentally inaccessible. Building on recent evidence from social neuroscience and psychology, Holmes argues that this assumption is problematic. Marcus Holmes studies some of the most important moments of diplomacy in the twentieth century, from 'Munich' to the end of the Cold War, and by showing how face-to-face interactions allowed leaders to either reassure each other of benign defensive intentions or pick up on offensive intentions, his book challenges the notion that intentions are fundamentally unknowable in international politics, a central idea in IR theory.