In 2003, mathematics professor Sergio Fajardo was elected mayor of Medellín, Colombia - one of the most violent cities in the world at that time. As mayor, Fajardo faced a host of daunting challenges. Rampant gang violence had raised Medellín's homicide rate dramatically, and a history of corruption had undermined the public's trust in the local government and law enforcement institutions. The under-resourced local police did not communicate clearly with the mayor, and the city was approaching bankruptcy. To address these concerns, Fajardo would need to not only develop a strategy, but also convince the majority of his 21-member city council - among whom he had only one ally - to support it. Fajardo needed to decide how to prioritize the many financial, legal, and cultural concerns in Medellín to bring the city closer to peace and prosperity.