On the morning of September 21st, eight gunmen showed up at a restaurant and abducted the owner's daughter in a car. Her family immediately called the army and police. But with the state's poor record of catching kidnappers in mind, they also called their friends and neighbours to pursue the criminals themselves. Some 20 people started giving chase, causing the kidnappers to crash two of their three vehicles and flee on foot.

Half an hour later, a mob then 200-strong found two 17-year-old boys they believed were part of the criminal group and began attacking them. The police managed to get the boys into a car and drive to a nearby army barracks. But the mob had grown to over 2,000 people, and some of its members used trucks to break into the barracks and drag their targets outside to be beaten. In a last-ditch effort to save the boys, federal police officers got them back into one of their cars and closed the windows. But they still died that afternoon. It is unclear whether they suffocated in the car or succumbed to wounds from the beating.

Vigilante justice is endemic in Guatemala, Mexico's southern neighbour, where criminal gangs have long acted with complete impunity. But Guatemala isn't far removed from a failed state, while Mexico is one of Latin America's richest and most stable countries—or at least it has been for the last 80 years. Last year, Mexican officials angrily denounced an internal Pentagon report that warned of the possibility of their country becoming a failed state. But if what happened in Ascensión on Tuesday doesn't count as nasty, brutish and short, I don't know what does. Mexico's murder rate is still modest by Latin American standards. But the drug war's downward spiral is starting to threaten the country's social contract itself.