ECKER AND LANCASTER paced the cafeteria, working from opposite ends of the space.

“So it makes sense an entrance would be in here,” said Lancaster. “Big room, get lots of students assembled in here and then down into the shelter in the event of an emergency.”

Decker nodded but said nothing.

She continued, “If it’s here it must be hidden behind something. Maybe the appliances?”

Decker shook his head. “It couldn’t be something that involved. With an emergency you have to have fast access.”

“But it was probably boarded up,” Lancaster pointed out. “Built over.”

“But the shooter still couldn’t be tearing into walls, floors, or ceilings, because that would also make noise and leave evidence behind of how he went from here to the back hall.”

“Well, he did leave evidence he was in here. The spoiled food, remember?”

“He did that on purpose. He could have easily turned the temp back down once he came out of it. Hell, he didn’t have to stay in the freezer all night anyway. He wanted us to know he was here. But he didn’t want us to find how he got from the front to the back. At least not right away. That’s the reason he left the trace in the ceiling and the tile dust on the floor. Classic misdirection. He’s screwing with us. And he’s costing us time. All good for him and bad for us.”

Lancaster kept glancing around. “So we’re looking for an entrance in here that’s been sealed up. We just don’t know how or where.”

“The term ‘sealed’ can mean a lot of different things. But the point is, our guy befriended Debbie for one reason and one reason only—to learn about this passage.”

“Come on, Decker. How would he even know about it to ask her?”

“I found out about it based on observations and hunches and a little research. He could have done the same. This is a relatively small town. He could have found out Simon Watson worked at the base any number of ways. He could have learned he once lived with the Watsons. He could have approached Debbie to see if she knew anything about it. And of course she did.”

“That takes a lot of planning and forethought.”

“And that apparently is a strong suit for our guy.”

Decker walked back and forth in front of a section of the wall.

Lancaster noted this and said, “I bet those rules haven’t changed in sixty years. I suppose you adhered to all of them when you went here?” she added with a smile tacked on.

The “rules” she was referring to were posted on a large section of the wall that Decker was studying. They included no loud talking, no throwing food, no eating off someone else’s plate, no milk cartons left on tables, all trash in the garbage, no running, and on and on.

“Amos, I said—”

He held up his hand for her to stay quiet, while he paced the wall and then looked at the floor.

“What do you see down there, Mary?”

She bent low and looked where he was pointing.

“Some marks. Probably from a student’s shoes.”

“I don’t think so. There’s no uniform requirement at Mansfield. Most boys wear sneakers. And from what I’ve seen, most girls wear sneakers, flats, or chunky heels. That footwear wouldn’t leave those sorts of marks. It’s actually scraped into the linoleum. And they’re not short, like a heel might make. They’re long. And they’re on a slight curve. Looks to be a few of them.”

“Well, what do you think they are?”

He stood closer to the section of wall where the rules were printed on a massive piece of wood painted to match the wall color. The wood ran down to the floor and nearly to the ceiling.

“No hinges evident,” he said. “But—”

He dug his fingers under the right section of the wall and tugged at various spots. He did this on the other side. Finally, after ten minutes of probing, tugging, and pushing, there was a little click and the entire section behind the sign opened outward. He pulled on it, opening it farther. Revealed behind it was a pair of old wooden doors painted the color of the wall.

“Look at the floor,” said Decker.

Lancaster noted another set of fresh scuff marks where the wood had dragged in one place across the floor when he’d opened the section.

“Damn, Amos. The mark on the floor was from the door swinging open.”

“Hinges were placed about a foot in and mounted on a support structure so they wouldn’t be visible to anyone. But the hinges have sagged a bit over time, hence the scuffed floor.” He ran his finger along one set of hinges and his finger came away darkened.

“Recently oiled,” he said.

There was a small knob in the center of the back of the section.

“What do you think that was for?”

Decker thought for a few moments. “You’d use it to pull shut the wall section once you’re on that side of it.”

“Right. But why even have a door at all? If they wanted to seal it up, why not just seal it up?”

“I don’t know, Mary. It must have cost a lot of money to build. Maybe they wanted to have reasonably easy access to it if they ever decided to use it again.”

“I guess.”

“I don’t see any fingerprints, but let’s not take chances. They call them latent prints for a reason.”

He grabbed a knife from a box of them on one of the kitchen counters to ease open the door by pushing back on the ordinary lock that secured the two doors. The door opened silently, showing that its hinges had been recently oiled too.

There was a long set of steps down into inky darkness.

Decker grabbed an emergency flashlight from a holder on the wall next to the serving counter and came back over to the doorway. “You ready?”

“Shouldn’t we alert the others?” said Lancaster nervously.

“We will, after we see where this goes.”

“But the FBI?”

“Screw the FBI, Mary. This is our case, not theirs.” He stared at her. “You with me?”

She finally nodded and followed him down the steps.

They reached the bottom, and here Decker stopped and shone his light around.

“Look there.”

They saw that set against one wall were two large sections of painted plywood. Bent nails were sticking out of them.

Decker said, “That’s how they really sealed up the passage. I saw nail holes in the perimeter around the double doors. That plywood had been nailed in front of the doors. If anyone figured out the sign opened, all they’d see is a solid wall.”

“You think the shooter did that?”

Decker shone his light on the floor. “Had to be. The sawdust on the floor looks relatively fresh. If he pulled out the nails the dust would come out and fall to the floor. Same when he hauled the sections down the steps. And he might’ve used a saw to cut through the wood too.”

“Which means he had to have done this before. No way is he tearing out wood walls during the school day. Too much noise.”

“He could have done it the night before. He comes out of the freezer and gets to work. No one here to hear anything. He opens the wall with the sign on it, cuts through the wall, opens the doors, and puts everything down in the passageway.”

“If he did all that, Amos, maybe that’s why he hid in the freezer.”

“Could be,” said Decker.

Decker pointed to the floor once more. In the dust were clear sets of shoeprints heading in the direction they were going.

Two clear sets of footprints heading down the passage.

“Walk to the right, Mary, so we preserve them. And take shots of them with your phone camera as we go.”

“Okay, but why two sets? Are they two different people?”

Decker bent down and shone the light on them. “No. The prints look to be identical. And it’s not two people walking side by side. The spacing of the prints is too close. But two sets make sense.”

“Why?”

“Come on.”

They continued on, with her taking pictures as they went. They passed through a massive, foot-thick metal door that only opened easily because it was set on hydraulic hinges.

“Some sort of blast door,” said Decker.

Now the space opened up into a large room about forty feet across and twice as long. The floors were concrete, the walls and ceiling the same. On the walls were signs that told what to do in the event of an emergency. Several were imprinted with a skull-and-crossbones symbol, the universal sign for danger. Along the walls were old metal lockers on which were bolted signs. One read, GAS MASKS. Another said, FIRST AID. A third said, WATER AND FOOD. The dust and cobwebs were pervasive and the air stale and musty.

“They must have had an independent air supply,” said Decker. “If a nuke hit, you couldn’t have access to the outside air.”

“But it can’t be airtight down here. I can breathe okay.”

“Which means it might have been vented so workers down here replenishing supplies and the like could breathe, but they close them off when the alarm sounds.”

Following the sets of footprints, they traversed the bomb shelter space and passed through another blast door where there was another passageway matching the one on the other side. The darkness was lifted every few seconds by the flash on Lancaster’s phone as she took pictures of the sets of shoeprints that had continued on down this passage.

Decker was counting off the steps in his head. Then they ran into another set of steps. These headed up. Decker had been shining his light on the floor at various intervals. The shoeprints they had seen earlier had paralleled them the entire way. They headed up. At the top of the steps was a blank wall.

“Dead end?” said Lancaster.

“Can’t be.” Decker dug his fingernails around the edges of the wall, working his way up and down both sides. Then he gained a handhold, tugged. The wall started to give, and then it came loose.

“It’s balsa wood,” he said, hefting it easily and setting it aside. On the other side of the open wall was a small space that was stacked with junk. On the other side of that was a door.

“The government wouldn’t have sealed it with balsa wood,” observed Lancaster.

“I’m sure they didn’t. But unlike the cafeteria where the wall wasn’t visible, this wall would have been in case someone opened that door. The shooter must’ve replaced whatever wall was here with the balsa. It would look solid but would be easily movable.”

“You’re talking a lot of work, Amos. He couldn’t have done all of that in one night.”

“But if he could access the school at night, he might’ve been here a lot doing what he needed to do.”

“But how would he do that? He couldn’t count on school plays every night? And bringing in saws and other equipment?”

“I’m not sure how he did it.” Decker hit the floor with his light. “Check out the patch right in front of the wall. Not much dust. That pile of junk used to be right in front of the wall, but it’s been moved so it doesn’t block the way.”

Decker checked the doorknob for prints, and then used the knife he’d brought with him to try to force the latch open.

“It’s locked. Give me a sec.” He passed the flashlight to her and pulled from his pocket his lock-picking instruments.

“Standard PI equipment?” she said wryly.

“You never picked a lock as a cop?”

A minute later the door swung open about a foot or so and then hit something.

“What is it?” whispered Lancaster.

Decker noted that she had her gun out. And that her left hand was still trembling.

“Something blocking the door.” He poked his head through the opening and recognized where they were.

“This is the storage room off the shop class. I looked in here before. The door’s hitting a stack of old window AC units. That’s why I didn’t see the door before. The units completely hid it from where I was standing on the other side.”

“And I bet when we searched this area, no one noticed the door on the other side for the very same reason.”

“Sounds right.”

Lancaster eyed the gap. “I can get through there.”

She turned sideways and passed easily through the narrow space.

She looked around. “If you can push on the door from your end, I’ll steady the AC units so they don’t fall over.”

He pushed on the door with his bulk and the door slid open farther, pushing the units with it, while Lancaster held on to them, keeping them upright.

“Okay, Amos, that’s plenty of room for you to get through.”

Decker passed through the widened gap, looked at the partially open door and then at the stack of AC units, and then stared down at the floor.

And then he frowned.

“What now?” asked Lancaster.

“There’s not a lot of dust in here, so I don’t see any more shoeprints.”

“But we saw the sets coming up the stairs. He had to come in here.”

“Agreed. So let’s assume he came through here and out into the shop class.”

They left the storage area and walked into the large room with all the tools and work tables.

“But how did the guy know there’d be no one in shop class?” said Decker.

“Oh, didn’t you know?” said Lancaster, sounding pleased she knew something Decker didn’t.

“Know what?”

“The shop teacher quit at the end of last year. They couldn’t find a replacement, so there’s been no shop class this year.”

“That’s why the door to the classroom was locked. And that’s also how the shooter knew. Debbie must’ve told him that there was no shop class.”

“But you were right, Amos. This is how he got from the cafeteria to the opposite end of the school unseen.”

“Which was why there were two sets of identical shoeprints,” added Lancaster.

“Right. Now, the shop class is also a big space, so maybe they figured to load kids from both ends of the school and down into the shelter in the event of an emergency.”

“How far underground do you figure that passage was?” she asked.

“Based on the number of risers, about twelve feet.”

“Doubt that would protect you from a nuclear bomb blast. Even if it’s all concrete with reinforced doors.”

He stared at her. “Well, what exactly would protect you from a nuke?”

“Good point.”

“I came in here the first night I was here looking around. Those are my shoeprints over there.” He pointed to the far wall. “I walked around, and then, like I said before, I looked in the storage rooms in the back.”

Decker knelt down and studied the floor. “Mary, hit this section with your light. I must have missed it earlier.”

Lancaster did so, revealing a long mark that disturbed the light dust, along with the impressions of shoeprints.

“What do you think that is?”

“Point your light about six inches to the left.”

She did. There was nothing.

“Try six inches to the right.”

She did and they saw an identical mark.

“What is that?” asked Lancaster.

“Marks from Debbie Watson’s feet.”

“Her feet?”

“Or her heels, rather, as she was being dragged out of here. The shoeprints are the shooter’s.”

“Out of here? What was she doing in here?”

“Meeting her beau. Her Jesus.”

“You aren’t serious?”

“Debbie was the first vic the ME did a postmortem on. Did you read the autopsy report?”

“Of course I did.”

“COD?”

“Why are you wasting time, Amos? Her cause of death was a shotgun blast to the face, as you very well know.”

“That was obvious. But did you note what the coroner found in her mouth?”

“You mean aside from shotgun pellets?” Lancaster said sarcastically.

“He found the residue of some breath mints.”

“Breath mints? I don’t remember reading that.”

“It was near the end of the report. I always read to the end.”

“But breath mints?”

“Residue of breath mints. There was a pack of them in her locker. Two were missing. That’s why she went to her locker. To get the mints. To freshen up her breath before meeting her beau. And her killer. And that would explain the time gap. He comes out of the freezer at seven-twenty-eight. He goes down the passage. But he has to wait for Debbie to get out of class. They probably had a prearranged time. She fakes being ill, gets her permissionslip, goes to her locker, gets her mints, and then enters the shop class.”

“But you said the door was locked?”

“Jesus would have unlocked it from the inside for her.”

“Right.” She eyed him suspiciously. “Exactly how long have you thought all this?”

“Not that long.” Decker closed his eyes and touched the back of his head about halfway down. “And the autopsy revealed that there was a subacute subdural hematoma on the back of her head, right about here. Left side of the occipital bone was cracked, and that’s a tough bone to damage like that. That might have killed her if the shotgun hadn’t, just from internal bleeding and resulting pressure on the brain. The ME speculated the injury occurred when she fell backward to the floor after being shot.” He opened his eyes and looked at his partner. “Left side.”

“Meaning the blow came from the left side and behind? A left-handed person? Like you said the guy who wrote the musical score was, left-handed.”

“The probabilities lie there, yes.”

“So he meets her in here and knocks her out, but why?”

“He needed her out of the way. And he needed to kill her first, before anyone else. He couldn’t risk the possibility that she would survive. She could identify him. So he arranges to meet with her, uses the passageway to get across the school unseen. I would imagine this is not the first time they’ve done this. They might have had sex in shop class during or after school on other occasions. I wonder how often Debbie got permission to go to the nurse’s office?”

“Have sex? Are you serious?”

“Their own private space in the middle of the school? What could be cooler for a teenager in love with her mature man who doesn’t even go here? And the killer would have wanted to know the passage by heart when he was planning this whole thing. He could bring stuff in and store it here. It was perfect.”

“So how do you see it playing out from there?”

“He meets in the shop class with her, she thinks to make out, hence the breath mints. He knocks her out, gets his gear, slips out of the room, walks around the corner to the camera, and gets his picture taken.” He glanced at Lancaster. “You saw the shoeprints in the passage?”

“You know I did.”

“I estimate they’re a size nine or maybe nine and a half, but no larger.”

Lancaster looked confused. “That’s not very big for a large guy,” she said slowly. “Earl’s six feet and he wears an eleven.”

“I’m six-five and wear a fourteen shoe, which is not unusual for a man my size. A guy six-two weighing in at two-hundred-plus pounds with a size nine shoe? Not likely. And I couldn’t get past the gap in the door with the AC units in the way. I had to push them out farther. And the lack of marks on the floor showed I was the only one who had. You got through easily enough, but you’re short and skinny. The guy in the video had a lot smaller waist than I do, but his shoulders and chest were just as broad as mine. So how did he manage to get through that gap without moving the AC units?”

“I don’t know. Do you?”

“I’ve got some ideas.”

Lancaster looked around nervously and chewed her gum so ferociously that her teeth were clacking together. “We need to get a forensics team in here. I hope to God we haven’t already tainted evidence. The Bureau will rip us a new one, after Mac finishes with us.” She looked around and then something seemed to strike her.

“Wait a minute. If the guy knocked Debbie out and then dragged her out of here, how did he shoot her standing up out in the hall? The ballistics was clear on that. She was upright. Blood spatters don’t lie. And there was only a minute gap between his picture being captured on the video and him killing Debbie.”

“There was a hole in the back of her jacket right where it would sit behind her neck,” Decker said. “He probably hooked the jacket on her locker door. It could keep her upright for a short time. He slips around the corner, gets his image captured on the video, comes back around the corner, and shoots her. The blast would have knocked her down. That’s when the jacket tore, when it was jerked off the locker door when she fell.”

Decker shone his light around the room and picked up more shoeprints, including a set leading back into the storage room and then back down to the passageway. There were also footprints in the shop class, belonging toDebbie Watson. She had worn clunky boots. They had been on her body. In the prints on the floor Decker could see a picture of activity forming. The two sets of footprints had gotten very close together. Probably when they had been kissing. She had been anticipating sex with the man she called Jesus, and instead she’d been thrown right into an early grave.

Decker leaned against the wall and rewound his DVR until he stopped at the point he wanted. “Did you notice something else down in the passageway, Mary?”

“Something else? Like what?”

He opened his eyes. “There were two sets of shoeprints going up the stairs to the storage room off the shop class.”

“Right.”

“And there was a set coming back down the stairs.”

“Right, again. So?”

“And while there were scuffed prints all over the place showing that he had used this passage before, there were no clear sets of shoeprints going back down the passage to the cafeteria to match the two sets coming from the front of the school to the back.”

Lancaster’s eyes widened. “Damn, that’s right. So how did our guy escape from the school?”

“Now, that’s a really good question.”