Paris’s Gare du Nord is one of the busiest international transit centers in the world. In the past three decades, it has become an important hub for West African migrants—self-fashioned adventurers—navigating life in the city. In this groundbreaking work, Julie Kleinman chronicles how West Africans use the Gare du Nord to create economic opportunities, confront police harassment, and forge connections to people outside of their communities. Drawing on ten years of ethnographic research, including an internship at the French national railway company, Kleinman reveals how racial inequality is ingrained in the order of Parisian public space. She vividly describes the extraordinary ways that African migrants retool French transit infrastructure to build alternative pathways toward social and economic integration where state institutions have failed. In doing so, these adventurers defy boundaries—between migrant and citizen, center and periphery, neighbor and stranger—that have shaped urban planning and immigration policy. Adventure Capital offers a new understanding of contemporary migration and belonging, capturing the central role that West African migrants play in revitalizing French urban life.