He had finished the last of his take-out dinner—a rather disappointing chicken curry. He didn’t have the luxury of a table, so a fair amount of it was dribbled down the front of his shirt and spattered on the marble floor around his boots.

Lethbridge eased back in his folding chair and loosened his belt a notch. The last of the curry completed the trek down his gullet, his head lurched back, and a tremendous belch burst through his lips. It shot up the walls like a gas-fired Ping-Pong ball.

“Whoops,” Lethbridge burbled to himself. “Pardon I.”

He removed a crumpled newspaper from the jacket that was slung over the back of the chair. Sighing, he settled in for a long night.

A half-moon shone through the glass dome that formed the roof high above, illuminating the cavernous circular room in a dull glow. Apart from the occasional scraping of Constable Lethbridge’s chair on the floor and the rustle of his paper as he turned the pages, there was nothing to be heard. As you might expect at two o’clock in the morning in the Reading Room of the British Museum, not a great deal was afoot.

The British Museum is one of the world’s finest museums. And the Reading Room is one of the museum’s finest rooms. Its walls are lined with bookcases that stretch up over three stories, and its elaborate glass-paneled dome is trimmed in gold and duck-egg blue. The room houses an extraordinary collection of leather-bound volumes of rare antiquity: a majestic warehouse of the learning of all Western civilization.

In the middle of all this sat Constable Lethbridge, scratching his bottom with the plastic fork from his dinner. There was nothing at all extraordinary about him. His sandy hair was thinning, his face was pale, he was on the tubby side of plump, and he was in desperate need of a holiday.

Lethbridge shifted uncomfortably in his chair. He lowered the newspaper to his lap and muttered, “Gawd, this is dull.”

His voice disappeared into the gloom. With a low grunt, he hauled himself to his feet, hitched up his sagging trousers, and shambled across the floor.

In the center of the room, bathed in moonlight and free from the museum clutter and dinnertime debris, stood a circle of identical statues. A dozen ancient archers carved from gray stone, each one aimed a crossbow at a black marble pedestal in the very middle of the room.

On top of the pedestal rested a glass case. And inside the case there shimmered a soft light.

Lethbridge stepped into the circle of stone sentries and crossed to the case. He bent down and peered through the glass.

Inside the case, on a stand like a red velvet egg-cup, nestled a single gem—a diamond—about the size and shape of a duck’s egg. Shards of moonlight hit the stone. Tiny rainbows reflected in Lethbridge’s watery eyes. The diamond looked as if it burned with a flame of gossamer in its heart.

“Not that impressive,” snorted Lethbridge, wiping a patch in the glass that his breath had fogged up. “Who’d pay a hundred million quid for that?”

He straightened up and plodded across the room, still clutching his waistband and grumbling to himself. He hated working nights. But with security guards on strike across London and police having to step in, his duty sergeant had assigned him the task of watching the diamond until dawn.

Lethbridge lumbered across to a large white sculpture of an elephant in the shadows at the edge of the room. The elephant was taller than a good-sized man and it sat plump-bellied and cross-legged on a cushion of pink rose petals. Garlands of blossoms were draped around its neck. Four arms poked out from its rounded sides; one hand held a coil of rope, another a bamboo flute, while a third clutched a bunch of roses. The fourth arm stretched out, like a cop stopping traffic.

Lethbridge peered into the statue’s face. The statue stared back. Their gazes locked.

Lethbridge went cross-eyed. He lost focus and half stumbled forward. He shuddered. Being locked in a huge circular room where the slightest noise seemed to come from every direction at once was giving him the creeps.

He turned and trudged back, his graying underpants peeking out above a drooping trouser line. At that moment the elephant statue blinked. A crusty white eyelid flickered. Hairline cracks spread across the statue’s surface, like a giant boiled egg being cracked with a teaspoon. Flakes of white plaster sprinkled onto the bed of rose petals as the elephant slowly began to move. It plucked a flower from one hand and guided it bud-first into the bamboo flute it held in another. Then it waited.

In the center of the room, Lethbridge passed between two of the stone archers and stopped in front of the glass case. He unhitched his belt again and bent over to take another look at the diamond. The back of his trousers sagged low.

A sharp burst of air splintered the silence. Lethbridge lifted his head. But before he could turn, something sharp buried itself deep in his left buttock.

He yelped, his eyes popping in their sockets in a rush of pain and surprise. He clamped his hands behind him to clutch at his underpants, out of which now sprouted a six-inch-long dart with a rosebud fixed to its end.

Lethbridge reeled. Grasping for support, he lunged at the glass case. His knees buckled. Numbness drained into his legs, his face flushed from red to purple. His jaw clamped shut and white froth spurted from his lips. His belt fell undone and his trousers collapsed around his ankles. Lethbridge lurched to the floor, crashing onto his elbows and knees, still hugging the glass case in his arms.

Across the room in the shadows, the elephant statue slid another flower into its flute.

Raising the instrument to its mouth like a blowgun, it let loose another bolt that shot across the room, this time skewering Lethbridge’s right buttock.

“Bleedin’ heck,” Lethbridge whimpered through clenched teeth. He laid the side of his stunned face on the cold marble floor. “That really hurts.”

His vision blurred. The world tipped on its edge and spun crazily inside his eyeballs. The numbness in his legs washed through him. The stone archers swam in and out of focus—almost laughing at him. Lethbridge could have sworn the elephant statue stood up from its nest of rose petals and took a step toward him. Then he blacked out.

And that is how Constable Lethbridge of the London Metropolitan Police was found by his colleagues the next morning: slumped facedown on the marble floor, asleep on his elbows and knees, his trousers around his ankles, his underpants exposed to the dome high above, and what appeared to be two red roses growing out of his backside.

Of the world’s most valuable diamond, however, there was no sign at all.