For decades, American hungers sustained Tijuana. In this scientific detective story, an award-winning public health expert reveals what happens when an entire city's heartline is brutally severed.Despite its reputation as a carnival of vice, Tijuana was, until recent years, no more or less violent than neighboring San Diego, to which it clings across a filament of border. But then something changed. Over the past thirty years, Mexico's third-largest city became one of the world's most dangerous. Tijuana's murder rate has skyrocketed, producing a staggering number of female victims. Hundreds of women are now found dead in the city each year, or bound and mutilated along the highway that lines the Baja coast.When Dan Werb began to study these murders in 213, rather than viewing them in isolation, he discovered that they could only be understood as one symptom among many. Environmental toxins, drug overdoses, HIV transmission: all were killing women at overwhelming rates. As an epidemiologist, trained to mine data to uncover the hidden drivers of a population's health, Werb sensed the presence of a deeper contagion targeting Tijuana's women. Not a virus, but some awful wrong buried in the city's social order, scything down its most vulnerable citizens. Werb's five-year search for the ultimate causes of Tijuana's femicide casts new light on immigration, human trafficking, addiction, and the true cost of American empire. It leads Werb from slums and drugs dens all the way to the corridors of cartel power and police corruption, as he follows a thread that finally takes a surprising turn back over the border, northward.