SEAN DROVE AIMLESSLY AROUND TUCSON BEFORE finally being drawn away from the city, south and west. By midday he was in Arivaca.

Arivaca was a tiny town twenty miles or so northeast of the border. It was a strange combination of cultures. Its heritage was cattle ranching, and there was open rangeland all around it. But he’d been told it had once been an artist’s colony as well, that various hippies and bohemians and artisans made it a home base during the winter. Some of that character still showed through-now and then roadside stands were set up with various arts and crafts for sale. Sean had once bought a tiger’s-eye gem from an old hippie couple that came right out of Central Casting, all the way down to the VW bus. He’d sent the gem to his sister.

Then there were the drug runners, the most notorious of which was Ray Acosta. An American citizen, he’d built a hugely ostentatious ranch-style house-all sleek modern lines, brick and glass-right in the middle of Arivaca, among the trailer homes and wooden frame houses. It stood out like a diamond surrounded by broken glass.

And now he was gone, over the border, leaving his palace behind. After the blown op yesterday, officers from three federal agencies had descended on the house. They found cash and they found guns, but no cocaine. Acosta was too smart for that, and now he was in Mexico.

Thanks to me, Sean thought, rubbing his forehead.

He pulled his Jeep Cherokee back onto the road, then crossed to the other side and parked under a tree. Just driving through, no one would know that Arivaca was the center of a war zone twenty miles from the border. The town’s single business, a little general store, seemed to do a brisk trade. A couple of arts and crafts tables were set up across the road from the store, and each had a few customers. Sean watched as a weary-looking man with a salt and pepper beard explained to the three young boys surrounding him that they could each have only one souvenir.

Sean smiled, then it faded quickly as he was aware of the jackhammers working behind his eyes. He dry-swallowed a couple of extra-strength Tylenol, then started the Jeep again.

“I never liked Arizona anyway,” he muttered, which wasn’t true. He recognized what he was doing, the process of rationalization. Like a child who didn’t get what he wanted, then insisted he’d never wanted it in the first place. He glanced at the man with the three boys again. Same principle.

The truth was, Sean loved the desert Southwest. He’d had a choice of assignments when he joined Customs seven years ago-Detroit, Seattle, or Tucson. Having grown up in the upper Midwest, Detroit held no allure for him. He didn’t care for rain, so Seattle was out. But the Southwest was exoticism and mystery and excitement, so he’d come to Tucson. And the work had been good. Confusing since September 11 and the creation of Homeland Security, but good work. Important. Even his old man, Detective Captain Joe Kelly, who was never pleased with anything, seemed to approve.

“Fuck,” Sean whispered. “Fuck it all.”

He pulled back onto the highway, heading west out of Arivaca. He could go anywhere. The trash bag full of stuff from his desk at ICE was in the backseat. So were his laptop and a small duffel bag with a few clothes and personal items. His career was over-he knew that. Thirty years old in a few weeks and his career was done.

“Fuck,” he said again, without much enthusiasm.

He drove through the rough country, some of it open range, some of it fenced as part of the Buenos Aires National Wildlife Refuge. It was a wild and beautiful terrain, mountains rising in hazy distance from the high desert floor. Sean drove on until the road dead-ended at the junction to State Highway 286, one of the loneliest stretches of two-lane highway he’d ever seen. A right turn would take him north, back toward Tucson. Toward “civilization,” whatever that meant.

A left turn meant Sasabe and the Mexican border. The town of Sasabe-though “town” was a generous description-squatted right on the border and was one of the two most isolated ports of entry along the southern boundary of the United States. One of Sean’s ICE colleagues-former colleagues, he corrected himself-was a woman agent, a fellow midwestern expatriate. She’d once told Sean that if “they” decided to cross the border at Sasabe, the authorities on the U.S. side wouldn’t have a chance. It was that isolated. She didn’t have to say who “they” were-drug runners, arms dealers, terrorists.

Sean’s own take on Sasabe was that it was really a Mexican village. It didn’t matter that it was on the Arizona side of the border. The flat-top houses, the adobe, the strings of peppers and onions hanging beside front doors, the gritty poverty. Sean thought a mistake had been made somewhere along the line, that the border had been moved half a mile or so too far south. It should have been redrawn so that Sasabe would be a Mexican border town, not an Arizona border town.

He turned left. Maybe he could start over in Mexico himself. His Spanish was good after seven years down here. He could live cheap in Mexico. Whiskey was inexpensive and easy to find. Maybe he could pick up Ray Acosta’s trail. Maybe, maybe, maybe…

He slowed the Cherokee to a crawl as he came into Sasabe. A little copper-skinned boy, maybe four or five years old, wearing only a pair of denim shorts, darted across the road as if he were playing chicken with Sean. A woman with three other kids surrounding her and a baby on her hip yelled in rapid-fire Spanish from a front porch. Sean nodded toward her. She stared at Sean unblinking.

Barely crawling at twenty miles an hour, Sean took the Cherokee around a sharp S curve. Ragged laundry hung on clotheslines on both sides of the road. More half-naked kids scampered. Sean wondered where they went to school, if at all. Ahead and to the left, looking like a well-dressed stranger that had wandered into the midst of all this, was the port of entry. A sign unnecessarily read MEXICO, with an arrow pointing the way.

The port of entry was all brick and stone and glass, a modernistic complex that straddled the road. There was no southbound stop sign. It was so simple to drive into another country. You just passed slowly through the port and then were in Mexico. Northbound out of Mexico was only slightly different. All an American citizen had to do was stop at the booth and declare his citizenship.

But Sasabe was different from other crossings along the border, places like El Paso or even Nogales, just a bit east of here. Traffic snarled in both directions in those places, Mexicans and Americans each seeing what the other had to offer. As for Sasabe, Sean had never seen more than one vehicle at a time come through this port.

Without even realizing it, he had pulled the Cherokee to the shoulder of the road, a hundred yards or so from the border. A green-and-white Border Patrol van drove past him, the driver staring out. Sean thought he knew the guy-he knew most of the BP officers and most of those who worked the ports of entry from Nogales to Naco to Sasabe.

He rubbed his head, waiting for the Tylenol to kick in. So far it hadn’t. If he crossed the border he’d have to pass by a booth where someone he knew would see him. Shit. More humiliation. By now every employee of ICE in Arizona would know how Sean “Irish” Kelly had screwed up and let Ray Acosta run. He didn’t know who was working down here today, but he knew them all. He’d even dated one of the women who worked the booth.

Very slowly, his jaw grinding, he wheeled the Cherokee back onto the road and turned it around, back to the north. He maneuvered the S curve again and again the little boy did his dance across the road in front of him. Again the mother screamed ineffectually and glared at Sean.