“Thom… Thom!” Rhyme shouted, startling everyone in the room.

The aide appeared in the doorway. He asked a belabored “Yes? I’m trying to fix some food here, Lincoln.”

“Food?” Rhyme asked, exasperated. “We don’t need to eat. We need more charts. Write: ‘CS-Two. Hangar.’ Yes, ‘CS-Two. Hangar.’ That’s good. Then another one. ‘CS-Three.’ That’s where he fired from. His grassy knoll.”

“I should write that? ‘Grassy Knoll’?”

“Of course not. It’s a joke. I do have a sense of humor, you know. Write: ‘CS-Three. Sniper’s Nest.’ Now, let’s look at the hangar first. What do you have?”

“Bits of glass,” Cooper said, spilling the contents out on a porcelain tray like a diamond merchant. Sachs added, “And some vacuumed trace, a few fibers from the windowsill. No FR.”

Friction ridge prints, she meant. Finger or palm.

“He’s too careful with prints,” Sellitto said glumly.

“No, that’s encouraging,” Rhyme said, irritated – as he often was – that no one else drew conclusions as quickly as he could.

“Why?” the detective asked.

“He’s careful because he’s on file somewhere! So when we do find a print we’ll stand a good chance of ID’ing him. Okay, okay, cotton glove prints, they’re no help… No boot prints because he scattered gravel on the hangar floor. He’s a smart one. But if he were stupid, nobody’d need us, right? Now, what does the glass tell us?”

“What could it tell us,” Sachs asked shortly, “except he broke in the window to get into the hangar?”

“I wonder,” Rhyme said. “Let’s look at it.”

Mel Cooper mounted several shards on a slide and placed it under the lens of the compound ’scope at low magnification. He clicked the video camera on to send the image to Rhyme’s computer.

Rhyme motored back to it. He instructed, “Command mode.” Hearing his voice, the computer dutifully slipped a menu onto the glowing screen. He couldn’t control the microscope itself but he could capture the image on the computer screen and manipulate it – magnify or shrink it, for instance. “Cursor left. Double click.”

Rhyme strained forward, lost in the rainbow auras of refraction. “Looks like standard PPG single-strength window glass.”

“Agreed,” Cooper said, then observed, “No chipping. It was broken by a blunt object. His elbow maybe.”

“Uh-huh, uh-huh. Look at the conchoidal, Mel.”

When someone breaks a window the glass shatters in a series of conchoidal breaks – curved fracture lines. You can tell from the way they curve which direction the blow came from.

“I see it,” the tech said. “Standard fractures.”

“Look at the dirt,” Rhyme said abruptly. “On the glass.”

“See it. Rainwater deposits, mud, fuel residue.”

“What side of the glass is the dirt on?” Rhyme asked impatiently. When he was running IRD, one of the complaints of the officers under him was that he acted like a schoolmarm. Rhyme considered it a compliment.

“It’s… oh.” Cooper caught on. “How can that be?”

“What?” Sachs asked.

Rhyme explained. The conchoidal fractures began on the clean side of the glass and ended on the dirty side. “He was inside when he broke the window.”

“But he couldn’t’ve been,” Sachs protested. “The glass was inside the hangar. He -” She stopped and nodded. “You mean he broke it out, then scooped the glass up and threw it inside with the gravel. But why?”

“The gravel wasn’t to prevent shoe prints. It was to fool us into thinking he broke in. But he was already inside the hangar and broke out. Interesting.” The criminalist considered this for a moment, then shouted, “Check that trace. There any brass in it? Any brass with graphite on it?”

“A key,” Sachs said. “You’re thinking somebody gave him a key to get into the hangar.”

“That’s exactly what I’m thinking. Let’s find out who owns or leases the hangar.”

“I’ll call,” Sellitto said and flipped open his cell phone.

Cooper looked through the eyepiece of another microscope. He had it on high magnification. “Here we go,” he said. “ Lot of graphite and brass. What I’d guess is some 3-In-One oil too. So it was an old lock. He had to fiddle with it.”

“Or?” Rhyme prompted. “Come on, think!”

“Or a new-made key!” Sachs blurted.

“Right! A sticky one. Good. Thom, the chart, please! Write: ‘Access by key.’ ”

In his precise handwriting the aide wrote the words.

“Now, what else do we have?” Rhyme sipped and puffed and swung closer to the computer. He misjudged and slammed into it, nearly knocking over his monitor.

“Goddamn,” he muttered.

“You all right?” Sellitto asked.

“Fine, I’m fine,” he snapped. “Anything else? I was asking – anything else?”

Cooper and Sachs brushed the rest of the trace onto a large sheet of clean newsprint. They put on magnifying goggles and went over it. Cooper lifted several flecks with a probe and placed them on a slide.

“Okay,” Cooper said. “We’ve got fibers.”

A moment later Rhyme was looking at the tiny strands on his computer screen.

“What do you think, Mel? Paper, right?”

“Yep.”

Speaking into his headset, Rhyme ordered his computer to scroll through the microscopic images of the fibers. “Looks like two different kinds. One’s white or buff. The other’s got a green tint.”

“Green? Money?” Sellitto suggested.

“Possibly.”

“You have enough to gas a few?” Rhyme asked. The chromatograph would destroy the fibers.

Cooper said they had and proceeded to test several of them.

He read the computer screen. “No cotton and no soda, sulfite, or sulfate.”

These were chemicals added to the pulping process in making high-quality paper.

“It’s cheap paper. And the dye’s water soluble. There’s no oil-based ink.”

“So,” Rhyme announced, “it’s not money.”

“Probably recycled,” Cooper said.

Rhyme magnified the screen again. The matrix was large now and the detail lost. He was momentarily frustrated and wished that he was looking through a real compound ’scope eyepiece. There was nothing like the clarity of fine optics.

Then he saw something.

“Those yellow blotches, Mel? Glue?”

The tech looked through the microscope’s eyepiece and announced, “Yes. Envelope glue, looks like.”

So possibly the key had been delivered to the Dancer in an envelope. But what did the green paper signify? Rhyme had no idea.

Sellitto folded up his phone. “I talked to Ron Talbot at Hudson Air. He made a few calls. Guess who leases that hangar where the Dancer waited.”

“Phillip Hansen,” Rhyme said.

“Yep.”

“We’re making a good case,” Sachs said.

True, Rhyme thought, though his goal was not to hand the Dancer over to the AG with a watertight case. No, he wanted the man’s head on a pike.

“Anything else there?”

“Nothing.”

“Okay, let’s move on to the other scene. The sniper’s nest. He was under a lot of pressure there. Maybe he got careless.”

But, of course, he hadn’t been careless.

There were no shell casings.

“Here’s why,” Cooper said, examining the trace through the ’scope. “Cotton fibers. He used a dish towel to catch the casings.”

Rhyme nodded. “Footprints?”

“Nope.” Sachs explained that the Dancer’d worked his way around the patches of exposed mud, staying on the grass even when he was racing to the catering van to escape.

“How many FRs you find?”

“None at the sniper’s nest,” she explained. “Close to two hundred in the two vans.”

Using AFIS – the automated fingerprint identification system that linked digitalized criminal, military, and civil service fingerprint databases around the country – a cold search of this many prints would be possible (though very time consuming). But as obsessed as Rhyme was with finding the Dancer, he didn’t bother with an AFIS request. Sachs reported that she’d found his glove prints in the vans too. The friction ridge prints inside the vehicles wouldn’t be the Dancer’s.