As she starts to walk away, Keller asks, "Anne Hathaway or Audrey Hepburn?"

"Oh, Audrey Hepburn. Of course."

Of course, Keller thinks.

Of course.

- "What do you think of the North American?" Martn Tapia asks as he steps out of the shower later that night.

Yvette sits in front of the mirror, carefully taking off her makeup and checking for wrinkles around the eyes that are as inevitable as they are undesirable. It might be time, she thinks, to check in with her cosmetic surgeon about Botox or a procedure.

"Keller?" she answers. "He's nice enough."

"Don't get fond. Adn wants him dead."

"That's a shame," Yvette says. "He could be useful."

"How?"

"Let me ask you something," Yvette says as she gets into bed. "Do you trust Adn?"

- Keller starts with Martn Tapia the next morning.

To all appearances, the middle Tapia brother is a successful young entrepreneur who does what successful young entrepreneurs do.

Most days Martn leaves the house midmorning and drives downtown. He has meetings, he has lunches, he has more meetings. He plays golf at the Lomas Country Club. He goes to banks and corporate offices. Some evenings, usually with his lovely wife on his arm, he's seen in trendy restaurants, at the theater, at the ballet or the opera. On other evenings they just stay home and enjoy a quiet dinner-the pool, the Jacuzzi, the tennis court-and retire early.

On Sundays, he and Yvette go to brunch at the Hotel Aristo with the other smart couples. Their list of friendships, acquaintances, and associates is a Who's Who of the capital. But after a month of surveillance, Keller never sees Martn meet with a policeman or a politician.

Maybe I'm wrong, he thinks. Maybe Martn is clean, not involved in his brothers' business. Or maybe he's taken some of the money and used it to launch himself in legitimate business.

Maybe.

Keller switches his attention to Yvette.

And again, to all appearances, she does what the wife of a successful young entrepreneur would do. She gets up and does yoga or swims laps, she takes tennis lessons from a private coach. She goes out to lunch with other wives, serves on charitable committees.

She plays golf.

Yvette Tapia is a serious golfer, going two or three times a week to the La Vista Country Club.

Keller can't follow her into the club without being stopped at the gate, but he parks across the road. Switching rental cars every day or so, he gets an idea of her schedule-every Monday, Wednesday, and Friday she drives her white Mercedes to the club, plays nine holes, and usually drives home, unless she goes somewhere to have a drink with friends.

Maybe I'm wrong, Keller thinks again.

The next afternoon, Keller doesn't track Yvette from the house but waits on the road outside the club for her to finish. This time she doesn't drive home or to a restaurant, but to a residential street that flanks the golf club.

Keller watches the white Mercedes pull into a driveway.

He notes the address-123 Vista Linda.

Probably a friend, Keller thinks.

He drives past and watches through the rearview mirror as Yvette gets out of the Mercedes, takes a small case from the passenger seat, and walks up to the front door. Then he pulls over on the other side of the street as she lets herself in with a key.

Jesus, he thinks, is Yvette Tapia having an affair?

But there's no other car in the driveway. Maybe, Keller thinks, the guy is cautious enough to park down the street and walk to the assignation. Feeling like a sleazy private detective, Keller shuts off the motor and waits.

If Yvette is having an affair, it lacks passion, because she comes right back out.

Sans suitcase.

Having to choose whether to follow Yvette or stay on the house, he decides on the house.

An hour later, a blue Audi pulls into the driveway and a well-dressed man who looks to be in his midthirties gets out and lets himself into the house. He's only there for a few minutes, then comes out with the small suitcase and drives away.

Keller gives him a few hundred feet, and then follows.

Yvette Tapia isn't having an affair.

She's a bagman.

- Keller could use help.

Surveillance isn't a one-man job.

It's hard to follow a car and not lose it or get "made," harder still to follow it through the labyrinth of heavy traffic that is the Mexico City metropolitan area, especially when you're relatively new to the area and don't know its intricacies. At least the Audi isn't trying to lose him-the driver seems confident, complacent, unaware that he might be followed.

That helps, but Keller knows that a successful surveillance operation needs a team-two or three cars to trade off the tail, a helicopter, communications and tech support. He could get any of this-all of this-through SEIDO or AFI, but...

...he can't.

For one thing, he's not supposed to be doing his own investigation, much less active surveillance. For another thing, he doesn't know whom he can trust.

Vera? Aguilar?

Every time-every time-they came close to Barrera, he slipped away. Then there was the Atizapn ambush. Did one or the other know? Did they both?

Keller could get some support from DEA, but he can't even go there because (a) he isn't supposed to be doing this, (b) they'd want to know why he isn't working with the Mexicans, and (c) he doesn't know whom he can trust.

For all he knows, this could be a setup and the blue Audi is leading him into a trap.

I'm bait, Keller thinks.

Now maybe the bait's been set for me.

He thinks of breaking off the tail. He has the license plate and could probably run it through EPIC without drawing too much attention. Find out who the driver is and proceed from there.

It's not a bad plan. Maybe smarter than losing the track now or, worse, getting made.

Or driving into an ambush.

The Audi takes a left.

It's the chance to let it go.

Keller follows.

The whole long way to Lomas de Chapultepec.

- The man tosses the car keys to the valet outside the Marriott and goes inside, the suitcase in his hand.

This is where Keller could really use a teammate, someone to go inside. If anyone in that lobby knows him, it's over. But he doesn't have an option, so he hands the valet his keys and some peso notes. "Keep it close."

He walks into the lobby and goes straight to the bar.

His man is sitting in the lounge with the case at his feet.

"A Cucap, please," Keller says.

He can see his man in the bar mirror. Watches him order a drink, watches as the waiter brings him what looks like a gin and tonic, watches as the man finishes his drink, leaves some bills on the table, and leaves.

The suitcase stays.

Seconds later, another man-in his forties, in a charcoal-colored suit-sits down, looks around briefly, and then picks up the suitcase and walks out.

Keller would give a lot for photographic surveillance.

He quickly pays for his beer, heads for the door, and watches the man get behind the wheel of a white Lexus. It's too late to get his own car and follow, but he does get the license plate.

The next morning, Keller runs both plates through EPIC. The first plate, the blue Audi that picked up the suitcase at 123 Vista Linda, is registered to a Xavier Cordunna, a junior partner in a Mexico City investment banking firm.

The second plate, the white Lexus that picked up the suitcase at the hotel, belongs to a Manuel Arroyo.

A commander in AFI.

- Keller punches in Marisol Cisneros's number.

"I was beginning to think that you'd forgotten it," she says when she answers.

There's a little starch in her voice and he hears it-this is not a woman used to being ignored, and she's going to let you know it.

"No," Keller says. "I just didn't want to be pushy. I'm sorry, I'm sort of out of shape in the dating thing. I don't know what the rules are anymore."

"I'll send you the book."

"Seriously?"

"Another nervous joke. Bad habit."

"So," Keller says. "I was thinking if we're going to have dinner alone, we could have it alone together."

"That was very good." Marisol laughs. "Did you practice that?"

"A little."

"I'm flattered."

"So...yes?"

"I would love to." Her voice is deep and sincere now-warm-and it sends a little jolt through him.

"Where would you like to go?" Keller asks.

"We could go back to your Chinese place," she says, "and redeem you in front of the waiters."

"It's kind of a dive. Maybe someplace nicer."

They settle on a little Italian place they both know in Condesa, and agree to meet there rather than for him to pick her up. "That way if we don't like each other," Marisol says, "it will be easier for one or both of us to escape."

There's no need to escape. Again, a little to his surprise, the conversation flows easily and he finds that he likes Dr. Marisol Cisneros very much.

Over linguine with clams, served family style, a mozzarella salad, and a bottle of white wine, he learns that she's originally from Valverde, a little town in the Jurez Valley just along the Ro Bravo. Her family has been there "forever," at least since the 1830s, anyway, when they were given land to settle in exchange for fighting the Apaches who were always raiding from the north.

The Cisneros clan has still been prominent in the Valverde area-not one of the "Five Families" that still dominate the valley, but more upper middle class than most of the people who live there-planting cotton and wheat down along the river, and running cattle and horses on the drier plateaus.

Marisol always knew she didn't want to be a ranchero's wife, so she studied hard and won a scholarship to the Universidad Nacional Autnoma de Mexico in Mexico City. Then she went to Boston University Medical School and did her residencies at Massachusetts General and Hospital Mexico Americano in Guadalajara, specializing in internal medicine.

She married a contract lawyer from Mexico City, moved back here, and went into practice with three partners in lucrative Polanco, although she volunteers time at a clinic in Iztapalapa.

"Rough neighborhood," Keller says.

"The people look out for me," Marisol says, "and it's only on Saturday mornings. The rest of the week, I take care of rich people's small complaints. But I've been talking and talking. What about you?"

He tells her a little more than he did at the Tapias' party, "confessing" that his job at the embassy is with DEA.

"We know a little bit about drugs in the valley," Marisol says. "The Jurez people have been operating there for years through the Escajeda family."

"Is it a problem for you?"

"Not really," she says. "Over the years, you work out a modus vivendi. You know how it is-you leave them alone, they leave you alone."

"I work mostly on bilateral policy issues," Keller says.

"I like the U.S.," Marisol says. "Let me see, I've been to El Paso, of course, San Antonio, New Orleans, and New York. Lived in Boston. Of these, I liked New Orleans the best."

Why? "I've never been."