“A few hundred.”

A relieved whistle escaped him. “Well, that’s not too bad.”

“A few hundred thousand,” Gray clarified.

“Oh, sweet motherfu—”

Kowalski’s reaction was cut off by the rattle of the doorknob. Gray started to turn, but Kowalski’s thick mitt of a hand grabbed Gray’s upper arm and yanked him back. He shielded Gray with his own body while smoothly pulling a .45-caliber pistol from a shoulder holster.

The slight figure of a young woman entered. She was fumbling with her purse, oblivious of the two in the room. She even swiped blindly for the light switch until she seemed to realize two things at once: the lights were already on and a massive mountain of a man had a pistol leveled at her chest.

She squeaked and backed into the jamb, unable to find the doorway in her fright.

“Sorry,” Kowalski said and shifted his pistol toward the ceiling.

Gray hurried around the befuddled bodyguard. “It’s all right, ma’am. We’re museum security. We’re investigating a break-in.”

Kowalski pointed his pistol at the shattered vase on the floor. “Yeah, someone broke that.” He glanced to Gray for confirmation and collaboration as he holstered his weapon.

She clutched her purse to her chest. Her other hand fixed a pair of petite eyeglasses higher on her nose. With her chestnut hair cut in a bob and her small frame, she appeared to be no more than a college sophomore, but from the crinkled pinch of her eyes, bright with suspicion, she was probably a decade older.

“Can I see some identification?” she asked firmly and kept close to the open doorway.

Gray held up his black I.D. pass. It displayed his picture, along with the presidential seal embossed in gold. “I have a number you can call to confirm who we are.”

She squinted at the pass and seemed to relax slightly, but a tension remained in her shoulders. She stared around the room. “Was anything stolen?”

“Maybe you can better answer that,” Gray said, hoping she could help. “I noticed that there seems to be a coin conspicuously missing from the table here.”

“What?” She hurried over, abandoning any hesitation. With one look at the table, her expression fell into a forlorn look. “Oh, no…we had the collection on loan from the Delphi museum.”

Delphi again.

She glanced to the carved dome of rock, the one that seemed to have attracted Polk’s attention. It may have been because Kowalski was leaning on it. “Please don’t touch that.”

Kowalski straightened. He looked at his palm, as if it were to blame. He had the decency to blush around the collar. “Sorry.”

“May I ask what that is?” Gray said casually, nodding to the stone.

Her hands wrung together with worry. “The prize of the collection. For the upcoming exhibit. Thank God, it wasn’t vandalized by the thieves.” She circled it to be sure. “It’s over sixteen hundred years old.”

“But what is it?” Gray pressed.

“It’s called an omphalos. Which roughly translates as “navel.” In ancient Greece, the omphalos was considered to be the point around which the universe turned. There are many mythologies and stories associated with the omphalos, great powers attributed to it.”

“And how did you acquire it?”

She nodded to the table. “It came from the same collection as the rest. On loan from the museum at Delphi.”

“Delphi? Where the Oracle of Delphi had her temple?”

She glanced toward Gray, her expression surprised. “That’s right. The omphalos graced the inner sanctum of the temple. Its most holy chamber.”

“And this is that stone.”

“No. Sadly it’s only a replica. Until just recently, everyone thought this was the original omphalos, as described in the ancient histories of Plutarch and Socrates. But the sisterhood of Delphic oracles goes back three millennia, and this stone has been dated to half that age.”

“What happened to the original?”

“Lost to history. No one knows.”

She straightened and strode over to a smock hung on a peg by the door. Donning it, she removed her museum identification tag from her shirt and fixed it to the smock.

It was only then that Gray noted the tag. It bore her picture and her name beneath it.

POLK, E.

“Polk…,” he read aloud.

“Dr. Elizabeth Polk,” she said.

A tingle of misgiving iced through Gray. He suddenly knew why the professor had come here. “By any chance do you know an Archibald Polk?”

She fixed him with a more solid stare. “My father? Why?”

3

September 5, 7:22 P.M.

Washington, D.C.

“Dead?”

Gray sat on the edge of the desk in the museum’s storage room. He knew the pain of what he had to tell her. Elizabeth Polk slumped in the chair, collapsed within her lab coat. There were no tears. Shock locked them away, but she took off her slim eyeglasses, as if readying herself.

“I heard about the shooting on the Mall,” she mumbled. “But I never thought…” She shook her head. “I’ve been in the cellars here all day.”

Where there was no cell phone reception, Gray noted silently. Painter had mentioned trying to reach Polk’s daughter. And she was right across the Mall the entire time.

“I’m sorry to press you on this, Elizabeth,” he said, “but when did you last see your father?”

She swallowed hard, starting to lose control. Her voice quavered. “I…I’m not sure. A year ago. We had a falling-out. Oh, God, what I said to him…” She placed a hand on her forehead.

Gray read the regret and pain in her eyes. “I’m sure he knew you loved him.”

Her eyes flashed to him, going harder. “Thank you for your words. But you didn’t know him, did you?”

Gray sensed the tough core hidden behind that mousy, bookish exterior. He faced her anger, knowing it was directed inward rather than at him. Kowalski had retreated to the far side of the room, plainly uncomfortable with the whole scene.

Gray twisted where he sat and pointed to the desktop. The rows of ancient coins still lined a paper blotter there. “I know because we found a coin on your father’s body.” Gray recalled what Painter had told him about it. “A coin with the bust of Faustina the Elder on one side and the Temple of Delphi on the other.”

Her eyes widened. She stared down at the gap in the row where the coin once lay.

Gray lifted an arm. “He came here before he was shot. To your office.”

“It’s not my office,” she mumbled, glancing around, as if searching for the ghost of her father. “I’m doing research for my doctoral dissertation. In fact, it was my father who pulled some strings and got me this graduate position at the Delphi Museum in Greece. I’d been out there until a month ago. I’m overseeing the installation of this exhibit. I didn’t think my father knew I was here. Especially after our—” She waved away what she was going to say next.

“He must’ve been keeping tabs on you.”

A few tears did flow, just enough to trickle down one cheek. She brusquely dabbed her face with the sleeve of her lab coat.

Gray gave her a moment. He stared over at Kowalski, who was walking in a bored circle around the stone omphalos, like a slow orbiting moon. Gray knew Elizabeth’s father had followed that same orbit. But why?

Elizabeth voiced the same question. “Why did my father come here? Why did he take the coin?”

“I don’t know. But I’m fairly certain your father knew he was being tracked, hunted.” He pictured Polk haunting the edges of the Mall, seeking some way of contacting Sigma in person, staying hidden. “He might have taken the coin in case he was murdered. The coin was grimy, easy to miss in a pocket if the assailant did a cursory search of the body. But a more thorough exam at a morgue would’ve revealed the strangeness of the coin. I think he hoped it would lead here. To this office where he would’ve known you’d report it stolen.”

The woman’s tears had dried as he spoke. “But why would he do that?”

Gray closed his eyes, thinking hard, putting himself in the man’s shoes. “If I’m right about the coin, your father was worried he would be searched. He must’ve known the hunters were after something. Something he possessed…”

Of course.

Gray opened his eyes and stood. He drew Elizabeth up, too. Her eyes studied the room, but not for ghosts this time. Gray saw the understanding in the pinch of her brows. She donned her eyeglasses.

“My father might have hidden here what his murderers were looking for.”

Gray headed to where Kowalski waited beside the conical-shaped stone. “Your father seemed particularly interested in the temple’s omphalos.”

Elizabeth followed with a frown. “How could you possibly know that?”

Gray briefly explained about the radiation exposure and lifted the Gamma-Scout. “Your father’s trail led here, and for me to get such a strong reading from it, he must have spent some time near the artifact.”

Elizabeth had paled a bit upon hearing of her father’s affliction. Still, she waved to Kowalski. “There’s an emergency flashlight plugged into that wall over there.”

He nodded and fetched it.

She approached the stone. “While it looks solid, it’s actually hollow inside. No more than an upended bowl of carved granite.” She pointed to the hole at the top.

Gray understood. Her father could have easily dropped something inside it. He accepted the flashlight from Kowalski, leaned over the stone, and pointed the beam down into the heart of it. It was indeed hollow. At the bottom, the slats of the pallet that supported the stone were illuminated. He shifted the beam around and spotted something off to one side. It looked like a polished stone, roughly the size of a cantaloupe.

“Can’t tell what it is,” he mumbled and straightened. “We need to lift the stone.”