The UAVs shot downward, entering a utility space populated by wires and pipes. The fit was excruciatingly tight, with bare millimeters of clearance at two points, plus a pair of tricky turns that looked like V’s with an extra leg curving down at the end. Turk knew he could not have flown this himself, but the tiny aircraft navigated the passage with ease, emerging in a large, empty chamber apparently designed for ventilation and heating equipment, but not used.

The lead nano-UAV curled upward as it reached the end of the long space, exploding just before touching the top. The force pushed down a second UAV, which had followed, adding momentum to its attack on the thick metal access panel that formed the floor. The explosion blew a hole in the panel, but unfortunately, the hole was not quite large enough to allow the next UAV to pass. The aircraft tangled its wings against a shard at the edge. Before Turk could react, it had blown itself up, enlarging the passage.

That had been one of the trouble spots Rubeo had warned of, a place where he feared they might lose one of the designated aircraft and have to rely on the backups. Two more lay ahead.

UAV 5 was now in the lead, projecting its infrared image to Turk as it passed through an open doorway and started down a ramp area, passing someone walking up the ramp. The Hydra twisted on its axis, completing a hard turn to its right to enter a work area roughly the size of a football field.

The screen blinked. A new set of words appeared at the bottom of the image: UPDATE: PROCESSING AREA.

A small forest of silver cylinders that looked like stacked coffeemakers sat on the south side of the large room. They were centrifuges, used to refine weapons-grade uranium.

That was a significant find, but Turk had not been briefed on it.

The next area contained a large bath, built to hold fuel. The site they hit the first night had a similar area.

This was starting to look like the place.

The swarm moved into an orbit at the top of the lab room, slowing while they formed themselves into two groups for the next leg of the assault. Turk debated whether to override—he could use one of the UAVs to destroy the centrifuges—but decided not to. If the attack was successful, they would be destroyed in the explosion.

UAV 5 tucked toward the floor, blowing out a stamped metal plate that covered an emergency drain. Seconds later the rest began to descend in a single line—until UAV 11, which struck something over the pipe and exploded.

UAVs 12 and 13 were caught in the explosion; there was a secondary explosion, and gas began hissing into the space. Fire destroyed UAV 14, and then UAV 15, disoriented, crashed into a centrifuge assembly.

Meanwhile, UAVs 16 and 17 plunged down the drainpipe unscathed, dropping toward the large holding tank at the east side of the facility. The tank had been punctured by UAV 6, opening the way into another large work space, about three-quarters the size of the centrifuge and pond area. The plan called for the swarm to move down another corridor into a lab area and from there to a second room that might be an assembly area, but Turk temporarily suspended it, putting the aircraft into a quick orbit around the top.

He closed his eyes and bent his head back, stretching his neck in a gesture of both prayer and despair. He didn’t have enough UAVs to complete the mission, and he had no idea how to improvise around the problem.

29

Over Iran

CAPTAIN VAHID SLOWED HIS MIG DOWN FOR A SECOND run near the hillside. The ground unit was on his left, the vehicle somewhere on his right. He hadn’t seen it on the first pass, though the soldiers on the ground claimed he had gone right over it. The rocks it was parked near—assuming it was there—obscured it on the radar.

He stared at the silvery ground, but it was just a blur.

“Fire a flare at the vehicle on my signal,” he told the Pasdaran commander. “Copy?”

“They will know they have been located.”

If they don’t know that by now, they are true imbeciles, thought Vahid. He told the commander to do as he’d asked.

Banking the MiG, Vahid told his wingman what he was doing and then began his run.

“Fire,” he radioed. A finger of red shot from the scratch road where the Pasdaran unit had stopped, leaping up the hillside into the rocks. Vahid saw something there, boxy, not moving.

The truck.

“Are you sure you want me to bomb it?” he asked. “You are very close.”

Surely it would make more sense for them to go up the hill and inspect it themselves. But Vahid guessed that the commander wasn’t willing to take that risk. If the truck was destroyed, there would be no way for the Israelis—or whoever was near it—to escape. He could wait for morning.

That was undoubtedly the idiot’s logic. He didn’t seem to calculate that whoever had driven it there was undoubtedly long gone, since the Pasdaran unit had not come under attack.

“Affirmative.”

“Pull back, then,” Vahid told them. “Radio when you are a safe distance away.”

“A waste of bombs,” said his wingmate. “But good practice.”

30

Iran

TURK STARED AT THE CONTROL SCREEN. THE SIX UAVS he had left were circling at high speed in the water overflow chamber, an unfilled water tank that was part of the cooling apparatus for a system designed to hold hot uranium rods. The gear was left over from an earlier, ultimately abandoned phase of the project’s experiments.

The UAVs were supposed to exit the massive tank through a small pipe, flying an intricate pattern through an emergency drain system and ventilation ducts before reaching the suite where the targeted lab was located. There, they would enter an air shaft, blast through a pair of ventilating fans, and invade the suite where the work chamber was located. It would take four UAVs to clear the way that far.

Once they had done their job, Turk would take direct control and fly the remaining UAVs to the target area. The chamber itself consisted of several small rooms. Turk would take the UAVs into a corridor through the opening in the ventilation shaft. He would then blast his way through a set of double doors and enter the targeted space. It would take three UAVs to clear the way. The last would strike the target at a point the Whiplash system calculated to do the most damage. Turk worried about this; even a slight delay from the computer as it relayed the information—or a problem with the link—might complicate the final task. Worst case, there might not be enough momentum left to initiate an explosion.

Unless the doors were open. If so, he could save several units and mass for the attack.

Turk hit the button at the bottom of the screen to bring up the view from the WB-57. The plane, under attack from the Iranian MiGs, was too far away to provide a live image. The screen warned that he was looking at a view frozen several minutes ago.

One door was open in the image, a technician passing through it.

Turk touched the screen and twisted his fingers, enabling a 3-D schematic view constructed from earlier radar penetrations. He moved it up and zoomed, looking at the area of the pipes.

The computer beeped at him, warning that the UAVs were getting close to the point where their flight momentum would no longer be enough to complete the mission.

Turk looked for another way into the final chamber. The ventilation shaft ran close to a utility closet at the end of the suite. It would take two UAVs to get there, then a third to get into the closet, and a fourth to blow out of the door.

Leaving two to get through three doors.

He moved the diagram, saw the utility closet at the base of a long chase of wires and pipes that ran up parallel to the chamber. If he blew into that chase, then had the UAVs descend, he’d use only five to get to the final target.