To his right he heard a the muffled chugging of a marine engine. Fifty yards away the gray, teardrop-shaped hull of the patrol boat was cutting across the surface, parallel to the fence. The boat’s wake fanned out behind it, spreading outward until it met the fence, where it curled back on itself and slowly dissolved. A spotlight clicked on and pierced the surface, turning the water around it turquoise.

Fisher waited until the boat crossed his front, then swam ahead. He had two minutes until the patrol boat returned. The sea fence appeared out of the gloom, a steel-cable net that stretched from its anchor bolts in the seabed to the linked buoys on the surface. Looking at the net, Fisher said a silent thanks to EPA, which had years earlier urged the Navy’s secure facilities to change the gap width of its sea fences so the indigenous fish population could come and go freely. In this case, the gaps were a foot square, which made Fisher’s job much easier.

He checked the time display in the upper-right-hand corner of his mask. Even as he did so he heard the chug of the patrol boat to his left. He flipped over and dove straight down, hand trailing over the fence until he reached the bottom. The boat passed overhead, spotlight arcing through the water and playing over the fence. Once it was gone, he ascended ten feet and went to work.

From his harness he pulled a “burn tie,” an eight-inch length of magnesium primacord. Ignited, magnesium burned hot and fast at five thousand degrees Fahrenheit, cutting through virtually anything it touched like a scalpel through jello.

He curled the tie around the cable before him, then jammed his thumbnail into the chemical detonator at the end and backed away. There was a half-second flash of blinding white light; the fence disappeared in a cloud of bubbles. When they cleared, Fisher swam ahead. The cable had been sheared neatly in two, turning the foot-wide gap into a two-foot-wide gap. He took off his rebreather harness, pushed it through the hole, then swam on.

TENminutes later he drew to a stop in front of shed’s steel door, a wall of corrugated metal painted battleship gray. He flipped himself upside down and finned downward. He switched on his task light.

The muddy seabed appeared before his faceplate. He turned horizontal and banked right. He passed the right edge of the door and then, abruptly, there it was: a circular scuttle set into the wall. He reached out and tried the hand wheel. Predictably, it was locked and, according to Grimsdottir, alarmed. If he tampered with it, he’d find himself surrounded by patrol boats before he got a hundred yards away.

“Anyone home?” Fisher radioed.

“I’m here, Sam,” Grimsdottir replied.

“I’m at the hatch.”

“Okay,” Grimsdottir replied. “Give me thirty seconds. I’m hacked into the Shed’s control room, but they’ve got the locks on an eight-digit public key encryption—”

“That’s nice, Anna, but maybe we save the technobabble for another day?”

“Yeah, sorry, hang on.” She was back a minute later: “Okay, locks and alarms are disengaged.”

“Going in,” Fisher replied.

The hand wheel was well oiled and it turned smoothly under his grip. He spun it until he heard the soft clank of metal on metal, then gently pulled. The scuttle swung open. Arms extended before him, he swam through.

His fins had barely cleared the opening when suddenly he heard the muffled shriek of alarm klaxons. In the distance, a water-muffled voice came over the loudspeaker: “Intruder alert . . . intruder alert. Security Alert Team to armory. This is not a drill! I say again: This is not a drill. . . .”

7

GRIMSDOTTIR’Spanicked voice was immediately in his ear: “Sam, I—”

Fisher reached up and hit his transmit switch twice, then once, telling Lambert and Grimsdottir, Radio silence; wait for contact.

In or out,he commanded himself. If he got out now, they’d lock the dock down and his chance would be lost. If he stayed on mission, he’d be facing a security force on high alert, hunting for an intruder. It was an easy decision. This is what he did.

He quickly shut the scuttle, then pushed off the wall and finned downward, hands outstretched. When he touched the rough concrete of the dock’s bed, he rolled to the right and kept swimming. He had one chance and one chance only. The shed was divided by a main watercourse bracketed on both sides by working piers. If he could find a hiding place deep within the pier’s pilings, he might be able wait out the security sweep.

Above him, the water went suddenly from dark green to turquoise as the dock’s security lights came on, bathing the interior in bright light. He heard the muffled pounding of boots on the dock and voices shouting back and forth to one another.

His fingertips touched wood: a piling. He hooked his arm around it and pulled himself under the pier. The water went dark again. He switched on his task lights and was engulfed in hazy red light. He kept swimming, weaving his way through the pilings. Covered in mottled gray barnacles, they reminded him of elephant legs.

Somewhere behind him he heard multiple splashes. Divers in the water. The dock’s security team was well trained and moving fast. Keep going.

The inner wall of the dock appeared before his faceplate. He looked up. Above his head he could just make out the understructure of the pier, a warren of crisscrossing girders and conduits.

Fisher finned around the piling nearest the wall, then switched off his lights and broke the surface. He shed his fins and clipped them to his harness. Now the hard part,he thought. Here was where all the hours of grueling exercise to keep his forty-something body in shape would pay off. He hoped.

Arms and feet braced against the wall and the piling, he began inching himself upward, using only the tensing of his muscles as leverage. Known in the mountaineering world as a chimneying, the manuever took supreme concentration. Fisher felt sweat running down his back inside the wet suit. His set his jaw and kept climbing.

Out in the watercourse he heard more splashing. To his left he saw a black wet-suit-covered head break the surface. A flashlight beam played over the pilings. Fisher froze. The beam passed over him, paused for a beat, then two, then three, then moved on. The diver turned and kept swimming.

Fisher pushed himself up the wall a few more feet and looked up. The understructure was within reach. He reached up, grabbed a water pipe, and let his legs swing free.

Somewhere nearby, a radio squelched: “Dock Boss, this is Diver Two-One. Approaching north wall, section nine. I’m going into the pilings. Thought I saw something.”

“Roger, Two-One.”

The diver had turned back. Hanging perfectly still, Fisher scanned his eyes left. The diver was there, head just above the surface, flashlight playing over the water as he made his way through the pilings toward him.

Quick and quiet, Sam. Go.

He tensed his abdominal muscles, drew his knees up to his chest, then hooked his ankles over the pipe and began inching his body along it until he was tucked tight against it. He looked down. The diver was almost directly beneath him.

With one palm pressed against a neighboring pipe for leverage, Fisher rolled his body until he was balanced lengthwise atop the conduit. He went still again. The diver’s flashlight appeared again, closer yet, casting slivers of light and broken shadows through the understructure.

Fisher closed his eyes and willed himself invisible.

Nothing here but us pipes, pal,Fisher thought. Swim along now.

After what seemed like minutes, but was likely less than twenty seconds, the diver clicked off his flashlight and finned away. Fisher let himself exhale.