The doorway provided cover, but just temporarily. It would only be seconds before the woman with the pistol stepped down the street far enough to have a clear shot at the two of them.

“Where to now?” Loren gasped, her heart pounding in fear.

Pitt quickly surveyed an ancient weathered door that stood at the top of the steps.

“A simple choice, I’d say,” he replied, nodding toward the door. “We go in.”

Two firm kicks on the wooden door were sufficient to dislodge the well-worn dead bolt from its housing and force an opening. Loren and Pitt quickly slithered into a plain, empty room, sided by a counter and cash register. At the back of the room was a wide, dimly lit stairwell that led to a lower level.

From outside the door, they could hear the sound of running footsteps approach. Pitt turned and swung the door closed as he caught a glimpse of the woman in black sprinting around the back of the taxi. He missed seeing the muzzle flash from her pistol as she fired again, but he saw the slug bury itself into the door a few inches from his face.

“I guess we go down,” he said, grabbing Loren’s hand and rushing to the stairs. They had hopped down a few of the carved stone steps when Loren yanked on his arm.

“I can’t make it that far in heels,” she said, noticing that the stairwell descended a considerable distance below them. She quickly yanked off her pumps, then proceeded to scurry down the stairs.

“Why does practicality never enter into the design of women’s shoes?” Pitt asked, catching up with her.

“Only a man would have to ask,” she grumbled, breathing hard from their exertion.

They continued plunging down the stairs, which descended over fifty steps. Their argument over footwear was lost to a sense of awe as their surroundings unfolded before them under sparse lighting.

They had descended into a huge man-made subterranean cavern. It was a totally unexpected and somewhat bizarre structure to find in the middle of bustling Istanbul. The steps ended at a wooden platform, which overlooked the deep cavern. Pitt admired a forest of thirty-foot-high marble columns that stretched into the darkness by the dozen, their capitals supporting a towering multi-arched ceiling. A bank of red overhead lights lightly illuminated the space, lending it a mysterious, almost hellish appearance.

“What is this place?” Loren asked, her voice echoing off the stone walls. “It’s breathtaking, in more ways than one.”

“It’s an underground cistern. A huge one, by the looks of it. The Romans built hundreds of them under the streets of Istanbul in order to store water, which was transported in from the countryside via aqueducts.”

They stood in what was actually the largest cistern in Istanbul, the Yerebatan Sarnici. Originally constructed by Emperor Constantine and later enlarged by Justinian, the structure stretched nearly five hundred feet in length. In its day, the cistern’s mortar-lined floor and walls were capable of holding 2.8 million cubic feet of water. Abandoned during the Ottoman reign, it became a forgotten, mud-filled bog until restored by the Turkish government in the twentieth century. As testament to Roman construction prowess, the floor of the cavern still stored a few feet of water for effect.

The vast chamber was nearly silent but for the splattering of water that occasionally dripped from the ceiling. The silence was suddenly disrupted by the sound of footsteps overhead as the armed woman in black rushed through the office and started down the stone steps. Pitt and Loren immediately took off running, following a raised wooden ramp that led toward the far end of the chamber.

The ramp ultimately split into a circular walkway that allowed tourists to view the myriad of carved columns that supported the cistern’s ceiling. Beneath it, the flat, shallow waters made a tranquil home to hundreds of colorful carp that never saw the light of day. Pitt and Loren had little time to admire the fish as they sprinted to the far end of the chamber.

The wooden ramps were wet from the dripping ceiling, and Loren slipped repeatedly in her stocking feet. Falling as they rounded a sharply angled corner, she lay for a second, catching her breath, until Pitt helped her to her feet. The sound of shoes rushing down the stone steps behind them echoed through the chamber.

“Why is she still bothering with us?” Pitt asked aloud as he dragged Loren around the corner.

“Might have something to do with this,” she replied, holding up the black bag still clutched in one hand. “I took it from the van. I thought it might be important.”

Pitt smiled at his wife’s instincts. “Yes, it probably is,” he said. “But it’s not important enough to get killed over.”

The pursuing footfalls had reached the bottom of the stairs, their tone changing to a muted thump on the wooden ramp. Pitt and Loren ran a few more yards, turning down a section of ramp that suddenly terminated in a dead end.

“Give me the bag, and you may walk away.”

The woman’s voice echoed through the cavern in angry repetition. After a silent pause, her steps resumed at a quickened pace. Though still out of view under the dim lights, she was audibly closing the gap.

“Into the water,” Pitt whispered, grabbing the black bag from Loren while guiding her to the rail. In her long dress, she clumsily climbed over the rail, then let Pitt help lower her quietly into the waist-deep water. Her body gave off an involuntary shiver, from both the cool water and the threat at hand.

“Move to the back of the far column and stay out of sight until I call for you,” he directed quietly.

“Where will you be?”

“Giving her the bag back.”

He leaned through the rail and gave her a quick kiss, then watched as she waded past several rows of marble columns before disappearing from sight. Satisfied that she was safely hidden, he turned and moved back down the platform. A thundering boom caused him to pause as a chunk of wooden railing splattered into the water a few feet ahead of him. He spotted the figure of the shooter a hundred feet away and he quickly sprinted ahead until a row of columns blocked her from view.

His mind raced in the few seconds of cover he had. He quickly contemplated the black bag, which was lightly weighed down by two separate objects. There was no place for concealment on the empty wooden ramps, so his eyes drifted upward at the huge columns nearby. He noted that every third column or so had a small red light fixture mounted near the crown, which backlit the cistern. As the sound of the woman’s footsteps drew closer, Pitt hoisted the bag and split the two objects through the exterior cloth. He then twisted the loose center cloth until the bag resembled a barbell, with the weighted objects at either end.

“Drop it!” he heard the woman’s voice yell.

In the dim light, Pitt gambled that she was still too far away for an accurate shot, so he took two quick steps toward the railing. The pistol barked again, twin muzzle flashes clearly visible out of the corner of Pitt’s eye as the shots thundered through the chamber. One bullet hit the rail while the other whistled past his ear. Already in motion, all he could do was keep moving.

With a third step, he swung the bag up from the floor and flung it upward with all his strength. Without breaking pace, he grabbed the top railing and pulled himself over the side. The bag spun like a pinwheel and was still drifting skyward when Pitt hit the water. He immediately spun under the surface toward the ramp, under its supports, kicking in the direction of the woman. With a controlled effort, he swam smoothly in the shallow water, trying not to break the surface. An old hand at free diving, he easily covered seventy-five feet before gently easing up for air.

He held perfectly still, quietly catching his breath beneath the ramp while checking where the woman was located. He correctly gauged that he had bypassed her beneath the ramp as she ran toward the point of his initial splash. Peering from the water’s edge, he saw her pacing on the far side with her gun pointed at the water.