Proofed by an unsung hero.

Above the horizon-spanning desert of Crockett County, Texas, lightning flashed against the sunset. Black thunderheads, touched by red and amber, stood like mountains against the sky.

Sudden raindrops splattered on the windshield of the Dodge. Al Horton, Federal Bureau of Investigation field agent, switched on the wipers. The rain died away as quickly as it had come. Horton flicked off the wiper switch and rolled down the window. The scents of rain and dust and mesquite filled the car.

Two miles ahead on Highway 10, silhouetted against the bloodred western sky, the semi-tractor trailer maintained a steady eighty miles an hour.

Horton glanced at a road map. He eased off on the accelerator. A thin, balding man, forty-three years old with a master's degree in public administration, a father of three children, Horton had no interest in tailgating a truck that was loaded with high-explosive ammunition.

The bureau's San Antonio office had issued a detailed directive to the four agents secretly tailing the truck:

Follow the shipment of weapons and ammunition. If the truck stops, radio the coordinates. If the truck stops at an airfield, radio the coordinates, wait for backup. If the truck nears the Mexican border, radio the coordinates, wait for backup. Under no circumstances attempt to arrest the occupants or seize the truck's cargo.

They didn't need to tell us that, Horton thought, smiling to himself. Four middle-aged office men with pistols and shotguns against gunrunners with automatic weapons? Right, boss, no heroes this week.

In the rearview mirror, Horton saw the headlights of the second car. He nudged his partner.

Lou Butterfield awoke, startled. He stared around blinking at the landscape of sand, creosote bushes and cactus that blurred past the car. "What's happening? Have they stopped?"

"Not them. What do you say we switch with Allan and Diehl? Let them take the lead for the next hundred miles?"

Butterfield took the map. He glanced at his watch then at the odometer to calculate the distance they had covered while he slept. Then he took the car's radio microphone. He faked an Old West voice.

"Well, partners, this is Deputy Butterfield. What say you all mosey on yonder. We'll meet up with ya at the Pecos."

A voice answered in somber tones. "This is a radio frequency reserved for the official communications of federal employees only. Persons engaged in unauthorized transmissions are subject to prosecution under sections..."

Laughing, Butterfield cut the other agent off. "Who is that talkin' back there? Sounds like one of them dudes from Washington, D.C."

The voice continued. "I will be brief. Will all the would-be cowboys get the hell off?"

"Cuttin' for the trailside," Butterfield continued. "Hasta la vista, cowpokes."

Recently transferred from the New York office, Lou Butterfield enjoyed taunting the Texan agents with AM radio cowboy jargon and pranks in the field. As Horton slowed the big Dodge, Butterfield joked about one of his cowboy pranks.

"Remember last month, maybe two months ago, we're following that low-life dope prince around town? And I show up for my shift in the sheriff suit?"

Horton laughed. Butterfield had arrived at the stakeout of the suspect's apartment wearing boots, faded jeans, leather chaps, a plaid shirt, leather vest, lawman's star and a ten-gallon hat. Diehl had threatened Butterfield with on-the-spot dismissal from the bureau if he did not change into a regulation three-piece suit immediately. But Butterfield, knowing from the previous night's monitoring of the phone that the suspect would meet friends at an "Old West" bar, refused to change clothes. At the bar, all the patrons wore phony Western gear. Of the four agents, only Butterfield could enter without inviting stares. He made the arrest, and received a commendation for his foresight in wearing the costume.

The Dodge slowed to a stop on the highway's gravel shoulder. Diehl and Allan sped past in their Volvo station wagon. In the distance, perhaps two or three miles ahead of the semi-tractor trailer they had been following, Horton saw approaching headlights. He thought nothing of it.

Horton walked from the highway, a moist desert wind chilling his sweat-damp slacks and white dress shirt. Around him, he saw the endless expanse of Texas leap from the darkness as lightning flashed.

Emptying his bladder into the sand, he surveyed the panorama of lightning and desert night. He searched the northern sky for the glow of the city lights of Midland and Odessa, more than one hundred miles away. Too early for that, he realized. He looked to the west and saw the last pink streaks of sunset fading from the horizon's storm clouds.

What a great place for a weekend, Horton thought. Rent an RV, take a side road way out to nowhere. Let the boys run wild. Him and Evelyn could carry Julie in a kiddie backpack. Take some long walks. Get away from all this bureau cops-and-robbers crap. Depending on the time of year. Later this month would be great. While it was all green. Before the sun and the heat burned it brown.

On the highway, the headlights of the approaching vehicle passed the semi-truck. The headlights drew nearer the car of the bureau agents following the truck.

Flame flashed from the headlights and the agents' Volvo exploded. The churning ball of gasoline fire rolled across the desert as the gutted car careered out of control.

"Butterfield!" Horton screamed. "The radio! They killed Allan and Diehl..."

Horton's smooth-soled wingtipped shoes slipped in the sand. He stumbled to his hands and knees, felt cactus spines jab his leg. At last he sprinted back to the Dodge.

Staring at the column of smoke in the distance, his eyes wide with panic, Butterfield was shouting into the microphone.

"This is Agent Butterfield on Highway Ten. They just rocketed the lead car. Repeat, rocketed. Diehl and Allan are dead. And now they're coming for us…"

"Out!" Horton screamed at his partner. "Get your shotgun."

Horton grabbed his eight-shot Ithaca 12-gauge from under a blanket on the back seat. He paused only to take a flashlight, then ran for the open desert.

Behind him, Butterfield shouted the number of highway miles from the last town, Ozona. Then he, too, grabbed his shotgun and sprinted through the gravel and mesquite.

"They said at least fifteen minutes before they can get a helicopter out here."

"Out there," Horton corrected him, pointing into the desert.

"Right!"

They ran through the darkness, distant lightning flashes throwing long shadows behind them. Horton, more agile and more familiar with Texas terrain, led the way. He dashed through gaps in the creosote brush, following the white pathways of sand. A lightning flash revealed the black slash of a gully.

Horton stepped off into it, sidesliding a few feet to the tangle of dry weeds and sand at the bottom. Butterfield hopped down an instant later.

A rocket shrieked. Punching through the Dodge, the warhead sprayed thousands of bits of exploding white-hot fragments into the night. An instant later, flames engulfed the hulk.

Tires screeched as a four-wheel-drive pickup fish-tailed to a stop on the asphalt. Four autoweapons flashed from the back of the pickup, the gunmen sweeping the burning Dodge and the roadside with bursts.

Crouching low in the gully, the two FBI agents ran north. Overweight and out of shape, Butterfield panted, stumbled. Acrid black soot from their burning car's tires clouded into the air above them. They heard the clang-crumpof 40mm grenades.