She checked in first with the head of her forensics team, Sergeant Herrera, who was clad in a white moon suit and white booties. “Anything yet?” she said.

Herrera shook his head. “Not much. This is the main public square of the town, so we’ve got a lot of residual cigarette butts and drink cans and things of that nature. We might get lucky and get some DNA off a smoldering cigar butt or the like. But there’s no brass I can find, nor blood spatter consistent with gunshot wounds. I believe these men were killed somewhere else and brought here already dead.”

He walked over to the edge of the plaza where a large pool of coagulated blood had attracted a cloud of hungry flies. “Except right here. Some of them were murdered right here. Dead corpses don’t bleed like this. We should be able to figure out from looking at them which ones they were.”

Garza nodded. “Anything else?”

“You see this?” Herrera pointed at the pavement with his booty toe. There were a series of strange divots in the pavement. “Just like the other ones. Same mark from the same blade. It’s him.”

Garza nodded. She knew these scars in the pavement. They all did. She had seen them in concrete, in soil, in wooden floors. She counted them twice. “Twenty-two,” she said.

“And twenty-nine corpses, yes,” said Herrera. “As before, whoever does the head chopping seems to enjoy his work very much. He is good at what he does.”

“Except for the guy in the ambulance,” Garza said. “He missed bad on that one.”

Sergeant Herrera agreed. He saw her glance at her watch. “Are we keeping you from something?”

Garza said with a smile, “Nothing, no.”

Herrera said, “You are going to Mexico City?”

Garza squinted at him through the strong sunlight. “You heard?”

He nodded. “They said you might become head of the Presidential Guard.”

That rumor was easy to shoot down. “The president must choose someone from the army, for political purposes.”

Cecilia Garza was indeed due in Mexico City in less than twenty-four hours, for a meeting with her old teacher from UDLA law school, also known as “the Harvard of Mexico.” Garza’s budding legal career had not worked out quite as she had planned or hoped, and she had turned from practicing law to enforcing the law soon afterward.

Her teacher’s fortunes had also changed. Just a few weeks ago, he had been elected president of Mexico. President-Elect Umberto Vargas was pressing her to join his personal protection detail, the EMP, Estado Mayor Presidencial. Though technically an army unit, it included fifty or so Policía Federal officers in its ranks. As far as Garza was concerned, the request was an honor but nothing more, and she planned to continue in her present capacity. But when the president calls and requests one’s service, one does as the president wants.

“He is single,” said Herrera. “You would make a fine first lady.”

Garza actually laughed, a rarity for her. “Yes,” she said, “that is the job for me.”

Vargas was a charming man—he was a politician, after all—but on top of being twenty years her senior, she had never felt any romantic impulse from him whatsoever. She realized, though, that tongues would wag. Dealing with that on the job would be the least of her problems.

One of Herrera’s white-suited forensic techs was methodically photographing the bodies. A pair of PF officers stood at each end of the row of bodies, scanning the empty plaza. The other man near them was Garza’s second in command, a big tough man named Major Alonso MacClesh. MacClesh was a common name in Mexico, thanks to long-ago Scottish immigrants—though, with his dark hair, high cheekbones, and black eyes, MacClesh looked as if he came from 100 percent Indian stock.

“Any witnesses?” she said. “Apart from the guy in the ambulance, I mean.”

MacClesh shook his head. He was smoking a cigar, the smoke trailing away from him in the warm evening wind. Garza had not trusted MacClesh at first. He was a hard man to read. He had been slotted to command the elite unit until Garza had been promoted over his head. If she had been in his shoes, Garza would have been pissed, so she trod gently around the man. But if MacClesh resented her, he never showed it. In fact, he never showed much of anything. His reputation, like his performance file, was stainless. Garza trusted him implicitly. But this was Mexico, the home of corruption, and you never knew anything for sure.

“Do we know who they are?” Garza said.

MacClesh pointed to a heavily tattooed torso—the arms and legs of which had also been cut off. “Tats say he’s Sinaloa. Probably a high-level guy. A lieutenant from Monterrey went missing last week. Ten to one that’s him. Alfredo Luis Jimenez. They call him Cinnamon.” He pointed at another legless, armless, headless corpse. “Probably Ronaldo Gutierrez, Jimenez’s bodyguard. Based on the tats on the next guy, probably also in Jimenez’s set.” He pointed down to the end of the row. “Four or five guys down there have tats consistent with the federal prison in Michoacán.” Michoacán was on the west coast of Mexico, where the Sinaloa Cartel was strongest. Most Mexican prisoners went to prison near where they were arrested.

“You’re saying these victims were probably from two separate snatches?”

“At least.” MacClesh puffed on the cigar. “Some of them, though, I don’t think had anything to do with gangs. Probably just random people they killed to pump up the body count. When tomorrow’s news says, ‘Zetas kill twenty-two members of Sinaloa Cartel,’ it makes the Zetas look strong and the Sinaloas look weak. The Gulf Cartel’s falling apart right now, so you got a lot of low-level players making up their minds whether they want to jump toward Sinaloa or the Zetas. This is the Zetas saying, ‘You want to play in this part of the world, you better sign on with our team.’ ”

MacClesh stubbed his cigar out on the sole of his boot, then slid it in his pocket. He didn’t want to drop his cigar butt on a crime scene. Garza liked that. Most Mexican cops—even in the elite PF units—had a contempt for physical evidence. And given how useless physical evidence generally was in the corrupt Mexican courts, she could hardly blame them. The PF went to a great deal of trouble to accumulate evidence . . . and it rarely proved the slightest value. Herrera and his men were trained by the Americans. They did their best. But it was mostly pissing in the wind.

“You know what this means, right?” he said.

Garza nodded, plucking her bottle of water from the loop on her belt and taking a swig. “The Sinaloas will retaliate soon.”

For a moment their eyes met. They said nothing. But she couldn’t help thinking she knew what they shared—the feeling that they were in a hopeless battle, that as long as Americans kept buying black market drugs, this madness would not cease. And there was a corollary to that recognition—the thought that maybe the battle wasn’t worth fighting, that it would be easier to look the other way, to stop fighting this uphill struggle.

During Garza’s college years, her mother and sister were kidnapped and held for ransom. The ransom was paid, but they were never returned. Suddenly the dry academic grind of writing contracts and filing real estate deeds had seemed to her an absurd waste of time. Despite the fervent opposition of her wealthy father, she joined the PF, naively determined to find her mother and sister’s killers. While she soon realized that the task was probably hopeless, she also realized that she had inadvertently found her calling. She had a natural talent for police work. But along the way she lost a marriage to a sweet young lawyer, became estranged from her father, and lost a lot of her old friends . . . and still found herself a social outsider in the lower-middle-class boys’ club of the PF.

Sometimes she wondered: What is the point?

MacClesh looked down expressionlessly at the dead. Finally he crossed himself. “I don’t mind when these animals kill each other. But this . . .” He shook his head. For a moment his face showed a rare expression of emotion: a mixture of sadness and disgust. “Who could possibly think this madness was a good idea? What kind of mind dreams up an abomination like this?”