On an afternoon in February 2011, two U.S. Immigration and Customs Enforcement agents were driving on a highway in central Mexico when they were ambushed by drug cartel gunmen. In the firefight that followed, one of the agents, Jaime Zapata, was killed - the first U.S. law enforcement agent to die in the line of duty in Mexico in more than a quarter of a century.

Mexican authorities quickly apprehended members of the Zetas, Mexico's most notorious criminal organization, who confessed to the murder. It looked like an open-and-shut case - until it was discovered that the guns used to kill Zapata had come from the United States, purchased by American gun buyers who investigators had been watching for months but hadn't arrested. For the federal law enforcement agencies still reeling from the Fast & Furious scandal, it seemed like a horrible kind of déjà vu.

Could Zapata's death have been prevented? Journalist Mary Cuddehe set out to find the answer. The extraordinary story of Agent Zapata traces the chain of events that led to the murder and explores its consequences, a journey that takes us from the seedy pawnshops of East Texas to the cartel-besieged cities of northern Mexico to the corridors of power in Washington, D.C.