"Is there a problem?"

Keller stops the tape. "I don't know, but I'm thinking that's Diego."

Aguilar nods and starts the tape again.

"Turning government policy around like that...it's going to cost more money."

"We pay you half a million a month."

Keller thinks Aguilar's jaw might break.

"It's not for us."

There's a silence, then Martn Tapia says, "We're willing to pay a reasonable bonus in addition to the normal payment, if that will help smooth over any rough patches."

"I'm sure it would help."

"I'd think they'd be pleased to go after La Familia. You can't do business with religious fanatics."

Aguilar stops the tape. "Who are they talking about? How high does this go?"

It's time, Keller thinks.

To decide if he trusts this man or he doesn't. If Aguilar is clean, he'll work with me. If he's dirty, this tape disappears and I'm a dead man. He takes a deep breath and then tells Aguilar all about his surveillance of Yvette Tapia, and how it led to the Amaros, and, by inference, to Los Pinos.

Aguilar takes it in, realizing that his closest colleague is dirty, then sits quietly. Keller watches him work it through, a man considering a chessboard.

It's vastly complicated, Keller knows. Aguilar can't know how high up the corruption goes, or how thorough it is. His boss, the attorney general, was appointed by the president. And is his own organization, SEIDO, clean? He doesn't know if he can trust the people he works for, or the people who work for him. It isn't just bureaucratic backstabbing-the chance of losing a job or even a career.

It's life and death.

They could kill him.

"Luis," Keller says, "you have a wife and kids. If you want to walk away from this, no one would blame you."

"I would," Aguilar says.

He gets up, and Keller hears him tell Lucinda that he's going out and doesn't know when he'll be back.

- They sit in a closed, locked room deep inside the SEIDO building and replay the tape again and again.

There are seven distinct voices at the meeting.

Martn Tapia is easy, but they still run it on voice recognition software against the tape of his phone calls from Cuernavaca, and it matches.

Aguilar locates old surveillance tape of Diego and matches that.

Then they run the voice that neither of them wants to run.

"Turning government policy around like that...it's going to cost more money." "It's not for us." "I'm sure it would help."

Aguilar places this on one track, then on another runs, "They surrender or they die. That's their only choice. Los malosos-the bad guys-are not going to run Mexico."

Keller watches the parallel lines spike on the voice recognition screen.

It's a match.

Gerardo Vera.

Aguilar doesn't even pause, but goes to work on the other voices. It takes hours, but he finds tapes of Bravo conducting an interrogation, Aristeo doing a press conference when he was first appointed, and Galven giving a speech to a community group.

Bravo, Aristeo, and Galven match with voices making small talk in the meeting.

"So," Aguilar says calmly, as if discussing a theoretical law school problem, "we have a thesis: The Tapias were the paymasters for the Sinaloa cartel. Vera and the others were on that payroll, as were high-ranking members of the administration. Then Barrera made his arrangement with us to betray the Tapias in exchange for his nephew. Somehow"-he looks pointedly at Keller-"the Tapias found out, creating a break in the cartel. The Tapias murdered three police officers, as well as Salvador Barrera, in revenge for Alfredo and to improve their position in a war with Barrera. They either wouldn't or couldn't get to Vera, nor did they anticipate that public backlash would strengthen the government, which they view as Barrera's ally, so they leaked a tape incriminating the dead officers and Vera."

Sounds about right, Keller thinks.

The question is what to do about it.

Aguilar's first instinct is to arrest Vera, but it's a rash move and rashness is not on his operational menu. Gerardo has surrounded himself with security in the wake of the assassinations, and there could actually be a gunfight between his AFI men and Aguilar's.

Besides, Gerardo has the ear of the president, at the very least.

The prosecutor in Aguilar takes over. The tape isn't enough to nail him-he could challenge that the voice is his, he could claim that yes, he was at the meeting to "set up" the Tapias-the proof being that he ordered the raids on Alfredo and Diego, and why would he do that if he were on their payroll?

"He's not," Keller argues, "he's on Barrera's payroll."

"Prove it," Aguilar counters.

They need witnesses, someone to wear a wire, they need a complete investigation into Gerardo's finances. "And that just takes us as far as Vera," Aguilar says. "What about the president's office?"

They have information that could bring down a government. And that government isn't going to investigate itself.

Which begs another question.

"Do you intend to turn this over to DEA?" Aguilar asks.

"It's what I'm supposed to do."

"This is not what I asked you."

It's tricky, Keller thinks. He works for DEA, not SEIDO; for the United States, not Mexico. He's holding crucial information that directly impacts DEA operations and investigations, maybe even the safety of undercover agents, if DEA is giving Vera information that he might pass on to Barrera.

Certainly, Keller thinks, Vera has passed on information about you.

And DEA could do what SEIDO really can't: conduct an independent investigation of the Mexican government. It has the surveillance technology, the ability to hack computers and break codes, intercept communications. SEIDO can do that-to a certain extent-but without getting caught? Who knows what worms have been implanted in the SEIDO machine?

So DEA can do it-and what they can't, the CIA or NSA can-but will they?

They're in love with Vera. If he were a woman they'd marry him, and his supporters in Washington-and they are legion-will argue that he's getting results. It might not even matter to them that he's getting those results for Adn Barrera, as long as he's taking down the Tijuana cartel, the Jurez cartel-and now the Gulf, the Zetas, and La Familia. Keller can hear Taylor say it now-So Vera's pulling in a half a million a month for taking down narcos? Good-we couldn't pay him that much.

You're being too cynical, Keller tells himself.

One of the two men in charge of antidrug operations is dirty? Of course DEA wants to know. The president's office implicated? That goes to the White House. Billions of dollars are being considered in a major aid program. To fight drug trafficking.

But he knows what Aguilar is asking and why. The SEIDO chief is a patriot, fiercely protective of his country, and now he's ashamed. And he'd be even more shamed if the U.S. Big Brother steps in to fix it, condemning Mexican corruption. It's the worst of Aguilar's nightmares.

"It's going to come out, Luis," Keller says. "You know that. If we don't act, the Tapias will find someone who will."

Brave new world, Keller thinks. In giving me the tape, the Tapia cartel is, in effect, applying for American aid.

"A few weeks," Aguilar says. "Let me do what I can to complete the investigation. If I can develop the evidence I need, I'll meet with your superiors. We'll go together."

Keller makes the deal.

- Three of the men in that meeting are dead.

But there was another voice on the tape.

A voice we haven't identified.

Who doesn't say much. A few times after Martn Tapia makes a point, you hear the voice agreeing, Chido. Chido.

Cool, cool.

They pull personnel records on every hire Vera made to AFI, and, since his promotion, to any federal police position, and find they have something else in common-all of them served together as beat cops in the tough colonia of Iztapalapa back in the '90s.

Galven was there.

So were Bravo and Aristeo.

They find three other high-ranking officers: Igor Barragn, Luis Labastida, Javier Palacios. All served with Vera in Iztapalapa, all were hired when he started AFI.

Now Barragn is the AFI coordinator for regional security.

Labastida is the director of intelligence.

Palacios is director of AFI special operations.

All under Vera's umbrella. All passed lie detector tests validating that they were clean.

Vera brought everyone up with him, Keller thinks, but who did he bring to the meeting with the Tapias? In all probability it was one of these three men, who has to be feeling the heat now that three others have been killed.

Or did he flip and join the Tapias?

In either case, he could be the witness we need.

They look for voice records on any of the three men but find nothing.

Something Keller's learned over the years-if the answer isn't in the present, it's usually in the past.

- You smell a slum before you see it.

Keller had a professor in college who said that civilization was a matter of plumbing. That basically, the infrastructure for moving clean water in and filthy water out is what allowed people to congregate in large populations in permanent dwellings and create cities and cultures. Otherwise, people had to be nomads to literally escape their own shit.

No such infrastructure exists in La Polvorilla, the worst slum in Iztapalapa. The smell of stagnant water is the least of it, the stench of urine and shit-dog, donkey, goat, chicken, and human-is an assault on the senses. The dirt streets are basically running sewers of shit and agua de tamarindo-"tamarind water," so called because of its brown color.

The lack of piped-in clean water demands a daily chore that only ensures that the women, at least, live in poverty. They wait for hours a day for the trucks to arrive, and on some days trucks don't make it at all because they've been hijacked in other Iztapalapa neighborhoods before they can get there.

Most of the "houses" are hovels-shacks and shanties with plywood walls and cardboard "roofs." Packs of feral dogs come out of the park at night looking for food. Most of the time it's garbage or a careless chicken, but the dogs have been known to carry away children.

The barrio is mostly famous for its dope, pickpockets, and prostitutes, and for an annual passion play that draws tens of thousands. I guess, Keller thinks, people will always show up to see someone put on a cross.

The streets are busy now.

Small-time drug dealers, hookers, gangs of kids. They watch Keller warily-he's not from here, doesn't belong here, only ventured into La Polvorilla to find a woman, buy heroin or coke.

Or maybe he's a cop.

Keller walks down a street, ignores the imprecations of the working girls and the kids selling mota, along the endless rows of shanties with tin roofs or old billboards serving the function of roofs.

He stops at a shack that has an old Coca-Cola sign for a door and pushes his way in.

The one room has a bare mattress and a single cane chair rescued from a garbage dump. A hot plate is wired to an old power strip-that and the single bare lightbulb hanging from the ceiling are connected to an illegal source in the street.

She's that rare creature, an old jaladora.

A crack whore.

Most of them don't live this long, Keller thinks, although it's hard to determine a crack addict's age. In their twenties they look like they're forty, in their thirties they look sixty, in their forties-if they live that long-they take on the indeterminate look of the very old. The wizened chin, the missing teeth, the vacant stare, which now looks at him blankly.

"Ester?" Keller asks. He's heard stories about her. Now it's taken him days to track her down.

Ester pats the mattress-an invitation. She offers him a half-and-half, an around-the-world, a hand job when she senses he isn't responding to the more expensive choices.

"Ester," Keller says, "you've been telling a story. About the policemen. About when you were young, and you were so pretty?"

"I was pretty."

"I bet you were," Keller says. "You're pretty now. Would you tell me the story?"

"Un diabolito," she says, demanding a cigarette laced with crack.

"After you tell the story," Keller says.

Ester sighs.

- She was pretty then and not a whore.