The City Spies head to the Big Apple when a credible threat is made to a young climate activist who is scheduled to speak in front of the upcoming United Nations General Assembly. With Rio acting as alpha and a new member in their ranks, the team's mission to protect a fellow teen takes them on an exciting adventure in, around, and even under the greatest city in the world as they follow leads to the outer boroughs, the UN Headquarters, and even the usually off-limits stacks that extend deep under the main branch of the New York Public Library.