This article historicizes and transnationalizes the phenomenon of national security whistleblowing. Challenging common interpretations that “blowing the whistle” represents an exclusive security or legal question, the essay explores the transnational connections and networks that have facilitated revelations in the public interest. Focusing on former-CIA operative Philip Agee, the article examines his exposures and wider campaign against the U.S. national security state – as well as its Latin American and European allies – through, across, and between nations. This struggle involved activists, publishers, artists, intellectuals, revolutionaries, peace movements, civil rights organizations, and ordinary citizens. The transnational nature of the protest was both a choice and a necessity as governments on either side of the Atlantic clamped down on whistleblowing. The state response focused on travel control and prior restraint as governments reasserted national security and secrecy privileges. Yet this overlooked the essential point that Agee’s whistleblowing developed and occurred over national borders. By exploring a peripatetic life, this article develops a history of whistleblowing, while contributing to literatures on transnational movements and protest networks, cultures of national security and secrecy, the U.S. and the world, American constitutional and international law, human rights, and the global cold war. It speaks to the possibilities and limits of dissent, the competing demands of national security and democratic transparency, and tensions between state power and civil liberties.