Stahl had just arrived at the office after a late lunch hour and sat down at his desk when a call on his radio distracted him. Team Four was on its way to a school in Brentwood, where someone had found a suspicious package in the cafeteria. Stahl stood and walked from his office and through Andy’s on his way out.

“I’m going out with Team Four to that call at the school.”

“Got it,” said Andy.

As Stahl hurried toward the elevator to the parking lot he was already thinking about the fastest way to Brentwood in mid-afternoon. He had chosen to go to the scene because a school was the sort of place this bomb maker might pick for his next attack. Stahl was aware that a school was also the most likely place for a false alarm. Kids made crank calls and staged misguided hoaxes, and only a very tiny number planted homemade devices. This was most likely a kid’s backpack with his sneakers and the remains of his lunch inside. But if it wasn’t, he wanted to see it.

Stahl got into his unmarked police car and drove. During the weeks since Diane was injured he had been going to the scenes of bomb calls more and more often. He’d carried a tool kit and a bomb suit in the trunk of his car in case he wanted to go downrange and examine the device that prompted the call.

Diane’s injuries had made him try to do everything and be everywhere. Part of the reason was that without her, he felt anxious and restless. Another part of the reason was that in the back of his mind he believed that not even an expert bomb technician was going to be as good as he was.

He had spent years at Eglin teaching military Explosive Ordnance Disposal specialists how to spot and defeat the most sophisticated devices, and since then he’d gone back for the refresher courses required to stay certified. He had kept up with whatever was newest and most formidable. Other people were almost certainly doing that too, but they couldn’t match the breadth of his experience.

This bomber seemed to him to require his personal attention. Everything he did was odd—eccentric and unfamiliar, but at the same time teasing and sadistic.

Diane’s bomb had been like that. The bomber had wanted to do more than just hurt her. He wanted to fool her, make her stand still where the bomb would be most powerful, and give her a moment or two to realize she had caused her own death. What Diane’s attack seemed to have done was change the bomber’s rhythm. Maybe he had been so pleased with his work at her apartment that he hadn’t been feeling the need to hurt anybody else right away. He had gone quiet for over a month.

All that time Stahl kept waiting and wondering what the next attempt would be. Stahl had gone on around twenty bomb calls and found nothing that seemed to be the murderer’s work. There was no device that would have presented a problem for any of Stahl’s twenty-seven technicians. The devices that weren’t fake were so crude that they would not have detonated if they’d been left in place forever.

Sometimes Stahl concocted stories to account for the bomber’s inactivity. The man had to be living somewhere far from other people, where his neighbors didn’t see or hear any of his testing or smell the chemicals, many of which had to be heated and cooled and reheated—and mixed with extreme care causing no friction, no buildup of static electricity, and no percussion. The bomber had been on a trend since his first crime, making and using more and more unusual and undependable mixtures in his bombs. Maybe on the day after rigging Diane’s apartment he had been making his next bomb and suffered an accident. Maybe he had neglected to ground himself often enough and shuffled his feet. That could build up a static charge in his body. Maybe this time he had sent stray voltage along the metal housing of his device, set off the bomb in his hands, and blown himself to atoms. Stahl hoped so.

Every morning when Stahl woke up he spent a second or two hoping that when he turned off his phone’s alarm he would see a text or an e-mail on the screen telling him a bomb maker had blown himself up. So far there was no such message.

It was Stahl’s job to assume the bomber had been busy preparing something bigger and more lethal. One possibility was that he was building many Semtex-powered devices. What was stopping him from planting fifty bombs in fifty places at once? Stahl knew this man was more likely to plant a hundred bombs than fifty. Each scene would have one to cause preliminary damage and a second one to kill the technicians and paramedics who would come later.

All the bomber had to do was keep the members of the squad moving fast from one call to the next to the next, until somebody got too tired to think and made a small mistake.

This bomb maker was versatile too. He could make bombs that looked exactly alike, but were triggered in vastly different ways. He could put one in plain sight and another under the only path to it. If he wanted to he could attach very sensitive bombs to immovable surfaces—bridges, staircases, large stone or steel monuments in public parks—with epoxy cement. There was no limit to what this kind of bomb maker could do. Each time a bomb was found, a bomb tech would have to walk up to it and decide what to do with it.

Stahl turned onto Williford Avenue and saw Team Four’s bomb truck just pulling up to the front of a large brick building that a sign identified as John Jay High School. The truck turned into a driveway and a police car that was parked across the entrance backed up to let it pass. Stahl approached before the officer could move back across the entrance, held up his identification, and followed the truck in.

He parked some distance from it and walked the rest of the way to join Team Four, who were climbing down from the truck and taking out equipment before entering the school. As Stahl approached he considered what he could see. This was a rich neighborhood. The houses he passed on the way were big and shaded by tall old trees.

He spotted Sergeant Paul Wyman, the supervisor of Team Four. Wyman was barely out of the truck when a middle-aged woman in a navy-blue business suit stepped up to him.

Stahl heard her say, “I’m Julia Cortez, the principal. All of the students have been evacuated to the next street over, where they’re waiting with the faculty in the supermarket parking lot. We’ve activated the phone tree to call their parents to pick them up.”

Paul Wyman said, “Very good. But we’ll need to double-check that the building is empty before we deal with the device.”

“I thought you might,” she said. “I can take you to where it is.”

“No, thank you,” Wyman said. “Just describe what was found and the exact location and we’ll take it from there. We have procedures that we need to follow.”

Stahl was pleased with the way Wyman was handling it, so he stayed a few yards off and kept listening. The principal said, “It’s in a black gym bag in the school cafeteria, which is in the back wing of the main building. This morning the teacher who was going to monitor the first lunch session saw the bag. He opened it to see if he could find the name of the owner and return it. Usually there will be something with the student’s name. This time what he found was a kind of bundle with a cell phone and wires and batteries. He left the bag and locked the cafeteria doors, then called me.” She handed Wyman a key. “This is the master key. It should open every door.”

As the members of Team Four prepared to enter the building, Stahl said, “Mind if I go in with you and take a look?”

“Not at all,” said Wyman. “We can use the help.”

“Good.”

The four police officers put on bomb suits and went in the front door of the main school building. Wyman sent Neil and Welsh to the main hallway to begin the search for stragglers or possible additional suspicious objects. They opened doors on either side of the main hallway and walked the perimeters of the first pair of classrooms, then moved on to the next pair of rooms. From time to time, one would call out: “This is the police. The school building has been evacuated. If you are still in the building come to the front door and gather in the parking lot. This is the police …”

Wyman and Stahl checked the rooms off the side corridors. When the four had made it all the way through the building they met where they had started. “The main section is clear,” said Welsh.

“The side sections are all clear,” Wyman said. “The captain and I will head for the cafeteria while you and Neil check the other buildings.”

“The cafeteria is down this hall near the back door,” said Welsh. “The doors are on the right.”

“All right,” Wyman said. “The captain and I will take a look and then we’ll meet at the truck.”

The two technicians went out the front door while Stahl and Wyman walked to the cafeteria. The room looked like the cafeteria of the middle school Stahl had attended over thirty years ago. There was a stainless steel and glass hot table three feet out from one wall, and the rest of the room was filled with long synthetic veneer folding tables that looked like blond wood, with five stackable molded plastic chairs on either side. They were all arranged in perfect order, with twenty tables to accommodate two hundred students at a time. Only one chair was pulled back from its table at an angle. It was on the far side of the room near where the hot food line would have been in an hour.

Wyman and Stahl approached, and Stahl stepped to the fourth aisle so he could see the one chair. “Damn,” he said. “It’s him.”

Wyman said, “How can you tell?”

“The gym bag. It’s just like the one he left on top of the elevator in the women’s health clinic.”

“Do you think he’s using the same kind of device?”

“It doesn’t sound that way. Didn’t the principal say it’s got a phone taped to it? This is the first one like that. Let’s take a look.”

He stepped close and peered into the half-opened gym bag without touching it. There was a beige brick of plastic explosive with a set of lead wires for a blasting cap running into it. He could see the cell phone and the corner of a lithium-ion battery. “The wires are the same color and style as the last ones—a number eight, probably from the same batch.”

“I was thinking,” said Wyman. “If we get the containment vessel up to the back entrance, we could just pop it in—even hand it out the window from here so nobody has to carry it far.”

“We can’t do that this time. It’s him.”

“What should we do, then?”

“Let’s get the jammer in your truck going.”

Wyman reached for his cell phone to call the others, but Stahl held his arm. “No phones, no radios until the jammer is running.” He let go of Wyman’s arm. “What model do you have with you?”

“TSJ-MBJ110.”

“Perfect. It’s been tested recently, right?”

“Once a week. We keep it charged and tested.”

They went out the back door of the school and headed for the bomb truck. As they did, Stahl focused his mind on the jammer.

This model jammer was designed for the military to prevent any radio signal, including a cell signal, from reaching a bomb and detonating it. The jammer had its own ten-thousand-watt AC generator, its own cooling system, and a battery backup. The jammer created a quiet zone for 150 meters around it, blocking every band from 20 to 250 megahertz. Once it was in place and operating, Stahl could go to work on the bomb.

Neil, Wyman’s second in command, set up the jammer in the central hallway of the school, plugged it into an outlet, and switched it on.

Stahl turned on his cell phone and waited for a signal, then put it away. “I get nothing. It’s operating. Thanks, Neil. Now go back to the truck, call a Code Five Edward and stand by while we figure out what we’ve got to worry about.”

“Yes, sir.” He went out the back entrance and headed for the truck.

Stahl and Wyman went into the cafeteria and Wyman stepped up to the gym bag.

“Don’t touch it just yet,” said Stahl.

“The jammer’s working. You tested it yourself.”

“Right,” Stahl said. “But this is the guy. Our guy. He doesn’t do just one thing. He’s well informed enough to know that if we suspected a phone trigger we’d use a signal jammer. He didn’t hide the phone.”

“But he hid everything in the bag.”

“Think for a minute,” said Stahl. “Why did this guy put the bag here? Not because he wants to kill a dozen middle school kids. He wants to kill some bomb technicians. So I’m guessing the phone isn’t the only trigger. It’s the bait. He’s hoping that once we neutralize the phone, we’ll think we’ve solved the problem. We’ll try to put it in the containment vessel.”

“That’s the logical thing to do. We can’t detonate it in a school.”

“So far he hasn’t planted anything that didn’t have a trap,” said Stahl. “So let’s see what he’s rigged to make normal procedures suicidal. Let’s start by checking for connections to anything else in the bag—wires, layers of an insulating material that are spring-loaded to pop out when someone touches the device and complete the firing circuit, pressure pads, tilt switches. He’s used all of those.”

They took out their flashlights and leaned over the bag, not touching it as they strained to see inside from every possible angle.

After a few minutes Wyman said, “No wires, or anything.”

Stahl said, “Agreed.” He lay on the floor and rolled onto his back to look up under the plastic chair seat. “Take a look at this, but don’t touch it.”

Wyman lay down on the other side of the chair and rolled to position the window of his helmet so he could see. “What is that?”

Stahl said, “It looks like the sensor mechanism from a burglar alarm. As long as the magnet on this side is touching this sensor, nothing happens, because the magnet is holding the circuit open. If the magnet gets moved, an interior spring pushes the sensor down and the gap in the firing circuit is closed.”

“So if we disconnect the battery, we’re done.”

“Let’s not assume that’ll do it,” Stahl said. “I’m not sure the battery has enough power to operate this.”

“You mean the battery is just another decoy?”

“Maybe not, but let’s see if there’s another power source.” Stahl reached into the kit and took out a multimeter. He put the leads to various spots and watched the dial on the box. “There’s power running through these two metal legs of the chair.”

He looked at the legs carefully, and then at two other chairs. “The feet of this chair are strangely clean—much cleaner than the others. No dust at all.” He touched the grout between the tiles of the cafeteria floor with his finger. Next he took out a knife from the kit and scraped the grout. It crumbled and began to come out.

“This grout is new. It hasn’t been here long enough to lose the moisture and set properly.” He worked at it a bit longer and then lifted his blade. “See the wire?” He pried up a double strand of narrow-gauge wire. “Let’s look for the other end of it.” He got to his knees and followed the line of fresh grout with his finger. It led to the nearest wall. He pointed to a small double wire with white insulation that ran a few inches up the white wall to the white cover of an electrical outlet. He used the knife to unscrew the two screws that held the cover to the wall, and saw that the two wires split and connected to the sides of the outlet. “Here’s the power source.”

“Can we disconnect it?”

“Yes.” He unscrewed one connection to the socket to free one wire, capped the end, and then freed the other wire. Then he took up the wire that ran under the grout. When he reached the chair he tested its legs again with the multimeter and found no current. He cut the two wires to the battery. Then he pulled the blasting cap out of the block of Semtex.

When Stahl had finished, he noticed that Wyman was looking around the room.

“Do you see something else?”

Wyman said, “If you hadn’t shown up, I would have died in this room.”

“Maybe,” said Stahl. “But now you’re less likely to die if you face this again. You just met this guy. Work on getting to know him, and how he thinks. Never forget that what he wants is to kill you and your team. Not some kids or a gas station attendant. He wants the tech who’s trying to defeat his bomb.”

“I was completely fooled,” said Wyman. “I never saw any of it.”

“Now you’re somebody this guy has to worry about. Pass it on to your team.”

“Thanks,” said Wyman. He knelt to begin picking up the tools.

“Leave everything where it is, including the jammer,” said Stahl. “We need to get the dogs in to sniff the rest of the school for explosives. He could have put another one in some kid’s locker.”

“I’ll make the calls and get the locker keys.”

“Right. If the dogs alert on anything, have somebody drive out of the zone and call me. If they don’t, you can turn the place over to the crime scene people. All we need is a print or some DNA, or a sign of where he bought the battery or the bags.”

Stahl clomped along the hall to the back door. He went to the bomb truck and said, “You’d better go in and help Sergeant Wyman. But don’t touch anything until he’s briefed you.” Then he went to his car, took off the suit, put it in his trunk, and drove.