The blue minivan crossed the runway and raced toward the line of maintenance hangars at Los Angeles Airport. From the rear of the nearest hangar, the yellow tail of the Transpacific widebody protruded, its emblem shining in the sun.

The engineers began to talk excitedly as soon as they saw the plane. The minivan rolled into the hangar and came to a stop beneath the wing; the engineers piled out. The RAMS team was already at work, a half-dozen mechanics up on the wing, wearing harnesses, scrabbling on their hands and knees.

"Let's do it!" Burne shouted, as he climbed a ladder to the wing. He made it sound like a battle cry. The other engineers scrambled up after him. Doherty followed last, climbing the ladder with a dejected air.

Casey stepped out of the van with Richman. "They all go right to the wing," Richman said.

"That's right. The wing's the most important part of an aircraft, and the most complicated structure. They'll look at it first, then do a visual inspect on the rest of the exterior. This way."

"Where are we going?"

"Inside."

Casey walked to the nose, and climbed a roll-in staircase to the forward cabin door, just behind the cockpit. As she came to the entrance, she smelled the nauseating odor of vomit.

"Jesus," Richman said, behind her.

Casey went inside.

She knew the forward cabin would have the least damage, but even here some of the seat backs were broken. Armrests had torn free and swung into the aisles. Overhead luggage bins were cracked, the doors hanging open. Oxygen masks dangled from the ceiling, some missing. There was blood on the carpet, blood on the ceiling. Puddles of vomit on the seats.

"My God," Richman said, covering his nose. He looked pale. "This happened because of turbulence?"

"No," she said. "Almost certainly not."

"Then why would the pilot-"

"We don't know yet," she said.

Casey went forward to the flight deck. The cockpit door was latched open, and the flight deck appeared normal. All the logs and paperwork were missing. A tiny infant's shoe was on the floor. Bending to look at it, she noticed a mass of crumpled black metal wedged beneath the cockpit door. A video camera. She pulled it free, and it broke apart in her hands, an untidy heap of circuit boards, silver motors, and loops of tape hanging from a cracked cassette. She gave it to Richman.

"What do I do with this?"

"Keep it."

Casey headed aft, knowing it would be worse in the back. Already she was forming a picture in her mind of what had happened on this flight. "There's no question: this aircraft underwent severe pitch oscillations. That's when the plane noses up and down," she explained.

"How do you know?" Richman said.

"Because that's what makes passengers vomit. They can take yaw and roll. But pitching makes them puke."

"Why are the oxygen masks missing?" Richman said.

"People grabbed them as they fell," she said. It must have happened that way. "And the seat backs are broken-do you know how much force it takes to break an airplane seat? They're designed to withstand an impact of sixteen Gs. People in this cabin bounced around like dice in a cup. And from the damage, it looks like it went on for a while."

"How long?"

"At least two minutes," she said. An eternity for an incident like this, she thought.

Passing a shattered midships galley, they came into the center cabin. Here damage was much worse. Many seats were broken. There was a broad swath of blood across the ceiling. The aisles were cluttered with debris-shoes, torn clothing, children's toys.

A cleanup crew in blue uniforms marked NORTON IRT was collecting the personal belongings, putting them into big plastic bags. Casey turned to a woman. "Have you found any cameras?"

"Five or six, so far," the woman said. "Couple of video cameras. There's all sorts of stuff here." She reached under a seat, came out with a brown rubber diaphragm. "Like I said."

Stepping carefully over the litter in the aisles, Casey moved farther aft. She passed another divider and entered the aft cabin, near the tail.

Richman sucked in his breath.

It looked as if a giant hand had smashed the interior. Seats were crushed flat. Overhead bins hung down, almost touching the floor; ceiling panels had split apart, exposing wiring and silver insulation. There was blood everywhere; some of the seats were soaked deep maroon. The aft lavs were ripped apart, minors shattered, stainless-steel drawers hanging open, twisted.

Casey's attention was drawn to the left of the cabin, where six paramedics were struggling to hold a heavy shape, wrapped in white nylon mesh, that hung near a ceiling bin. The paramedics adjusted their position, the nylon webbing shifted, and suddenly a man's head flopped out of the mesh- the face gray, mouth open, eyes sightless, wisps of hair dangling.

"Oh God," Richman said. He turned and fled.

Casey went over to the paramedics. The corpse was a middle-aged Chinese man. "What's the problem here?" she said.

"Sorry, ma'am," one of the medics said. "But we can't get him out. We found him wedged here, and he's stuck pretty good. His left leg."

One of the paramedics shined a light upward. The left leg was jammed through the overhead bin, into the silver insulation above the window panel. She tried to remember what cabling ran there, whether it was flight critical. "Just be careful getting him out," she said.

From the galley, she heard a cleanup woman say, "Strangest damn thing I ever saw."

Another woman said, "How'd it get here?"

"Damned if I know, honey."

Casey went over to see what they were talking about. The cleaning woman was holding a blue pilot's cap. It had a bloody footprint on the top.

Casey reached for it. "Where'd you find this?"

"Right here," the cleaning woman said. "Outside the aft galley. Long way from the cockpit, isn't it?"

"Yes." Casey turned the cap in her hands. Silver wings on the front, the yellow Transpacific medallion in the center. It was a pilot's cap, with a stripe for a captain, so it probably belonged to one of the backup crew. If this plane carried a backup crew; she didn't know that yet.

"Oh dear me this is awful just awful."

She heard the distinctive monotone, and looked up to see Doug Doherty, the structural engineer, striding into the aft cabin.

"What did they do to my beautiful plane?" he moaned Then he saw Casey. "You know what this is, don't you. It's not turbulence. They were porpoising."

"Maybe," Casey said. "Porpoising" was the term for a series of dives and climbs. Like a porpoise leaping in water.

"Oh yes," Doherty said, gloomily. "That's what happened. They lost control. Terrible, just terrible…"

One of the paramedics said, "Mr. Doherty?"

Doherty looked over. "Oh don't tell me," he said. "This is where the guy got wedged?"

"Yes, sir…"

"Wouldn't you know," he said, gloomily, moving closer. "It had to be the aft bulkhead. Right where every flight-critical system comes together to-okay, let me see. What is it, his foot?"

"Yes, sir." They shone the light for him. Doherty pushed up against the body, which swayed in the harness.

"Can you hold him? Okay… anybody got a knife or something? You probably don't but-"

One of the paramedics gave him a pair of scissors, and Doherty began to cut Bits of silver insulation floated to the ground. Doherty cut again and again, his hand moving quickly. Finally he stopped. "Okay. He missed the A59 cable run. He missed the A47 cable run. He's left of the hydraulic lines, left of the avionics pack… Okay, I can't see he hurt the plane in any way."

The paramedics, holding the dead body, stared at Doherty. One of them said, "Can we cut him out, sir?"