The area near where Han Xiling had been attacked was a maze of alleys and hutongs, and Zheng Yun and Bai Jin lost the perpetrators in the tangle before long. The two returned to the Military Police Department deflated. Shi Ting had only just arrived as well.

It was nearly three in the morning, yet the Military Police Department was still ablaze with light.

Shi Ting walked to the blackboard, erased several lines with the chalk eraser, and drew new ones. “The perpetrators know this area with extraordinary familiarity. We can say with reasonable certainty that they live somewhere in the Lucheng district.”

This district fell within the triangular zone Shi Ting had previously mapped out — confirming, broadly speaking, that his geographic analysis had been sound.

Zheng Yun said, “The residents of the Lucheng district are a mixed lot. It won’t be easy to narrow things down.”

At the time of the chase, the group had been some distance away, and in the poor nighttime visibility they had only been able to make out two silhouettes — one tall, one short; one stout, one lean. Trying to find two individuals based on build alone was going to be difficult.

“First thing tomorrow morning, we go door to door,” Shi Ting said, his gaze unyielding. “Every household, including the cellars. No one gets missed, no one gets overlooked. However hard it is, we will find these two men.”

“Yes, sir!” Both officers rose and saluted.

“Go home and rest first.” Shi Ting set the chalk back in its tray. “I’ll drive you.”

—

The next morning, just as dawn was breaking, birdsong trickled in through the window.

Jin Shan, the household attendant, stood at the doorway and said quietly, “Young Master, Second Yitai has come.”

Before he had finished speaking, Shi Ting — already fully dressed in his uniform — pulled the door open. “Mother, you’re up early.”

His second mother, Luo Huaimeng, stepped quickly into the courtyard. “I was afraid of missing you if I came any later.”

Shi Ting glanced at his watch. “Is there something urgent, Mother? I need to get back to the department.”

“I heard that Minister Han’s daughter was injured. Is it true?” Luo Huaimeng’s tone carried a trace of reproach. “Minister Han’s daughter came to the Military Police Department for training — why didn’t you look after her? You could have found her something simple to do, like clerical work, rather than involving her in anything dangerous.”

“She took matters into her own hands,” Shi Ting replied, his expression unchanged. “Is that all, Mother?”

“You’re still playing innocent with me, and I know perfectly well you won’t have missed my visit with Minister Han’s wife.” Luo Huaimeng’s voice took on a more earnest tone. “Minister Han holds the financial authority over Bei Di and is one of the Commander’s most trusted men. A match with his family would be a great advantage to your career.”

“I have no interest in Han Xiling.”

“Your marriage was always going to be a matter of practical exchange. The woman you choose only needs to be of benefit to your career — there’s no need for genuine affection. If you find someone you truly care for later on, you can bring her in as a yitai. You can take as many as you like.”

“The woman I marry will be someone I love.” Shi Ting’s tone left no room for argument. “Mother, there’s nothing more to discuss on this matter.”

“Why won’t you listen to reason, child? I’m saying all of this for your sake.”

“I know my own mind.” Shi Ting gave Luo Huaimeng a slight nod. “Please don’t trouble yourself over this.”

Finding her persuasion had come to nothing, Luo Huaimeng gestured to her maidservant, who stepped forward carrying a tray. On it sat a small round porcelain bowl. “This bird’s nest soup was prepared on my orders — I had it made with codonopsis root and wolfberry. Good for the spleen and to replenish your energy. Drink it before you go.”

Shi Ting accepted Luo Huaimeng’s gesture without objection, taking the bowl from the maidservant and eating it as he stood.

Luo Huaimeng couldn’t help but let out a small complaint. “The bird’s nest allocated to each household from the Shi Family is supposed to be the finest grade, and yet what makes its way to my courtyard is always the inferior sort. My station is too low to say anything about it — all I can do is swallow my grievances. The bird’s nest in Third Yitai’s quarters, on the other hand, is the best of the best — even better than what the First Madam receives — and at a staggering price. I’ve heard that the people who gather bird’s nests have a very hard time of it. These birds build their nests on sheer cliff faces, and collectors have to climb up by hand to reach them. Men fall to their deaths doing this, so perhaps it isn’t unreasonable that the price reflects the difficulty…” She trailed off. “Xingzhi! Where are you going? You haven’t finished the soup!”

Shi Ting placed the bowl on the tray. “Mother, I have pressing business. I have to go.”

At the doorway, he paused and turned back. “Thank you.”

Luo Huaimeng watched him hurrying away and sighed to herself. “What’s all this ‘thank you’ business? This child, really — at least finish the soup before you go.”

—

Shi Ting went straight outside, where a car was already waiting. Ferrying him to and from work each day was the responsibility of their driver, Old Zhao, who could navigate every road in Shun Cheng from memory and find any address Shi Ting named with perfect accuracy.

Bai Jin was already in the back seat, bleary-eyed and leaning drowsily against the headrest. He sat upright at the sound of the door. “Seventh Brother.”

“I know what the murder weapon is.” Shi Ting’s eyes lit with a spark of excitement.

“What?” Bai Jin’s sleepiness evaporated instantly.

“A mountaineering axe.” Shi Ting had seen this tool before but hadn’t made the connection at the time. When Yan Qing described the shape of the weapon, the image hadn’t surfaced from his memory fast enough. But just now, when his second mother mentioned the workers who gathered bird’s nests — men who had to climb sheer cliff faces to harvest them — and the tools they used to do it, everything fell into place.

The tool was custom-made: one end curved into a sharp, backward-facing hook designed to catch in the crevices of rock faces, and the other end was axe-shaped for chipping away obstacles to the climb. Skilled workers, using this in combination with a rope, could scale sheer rock faces with relative ease.

“Old Zhao, head to Chengguan Street.”

Old Zhao had all of Shun Cheng’s roads committed to memory. Whatever Shi Ting instructed, he could navigate to the exact address.

On Chengguan Street there was a bird’s nest shop — one that both harvested and sold. The shop handled the full process from collection to retail.

It was still early, and the shop had not yet opened. Bai Jin knocked at the door. The owner, freshly woken and not yet in a pleasant mood, peered out through a crack. “Who are you?”

“Military Police Department.” Bai Jin held up his credentials. “We’d like your cooperation with an investigation.”

Upon hearing Military Police Department, the owner immediately swung the door wide open. “Ah, officers — please, come in, come in.”

The Military Police Department enjoyed considerable standing among the general public, and ordinary people had nothing but admiration for it.

“Officers, has the headbanging perpetrator been caught?” The case had been on everyone’s lips for days.

“If you cooperate, we won’t be far off.”

The owner perked up at once. “Of course, of course, happy to help.”

Shi Ting stepped inside and took in the shop. Though small, the display cabinet was lined with bird’s nests of every variety — some hand-processed to remove every last feather, others still mixed with impurities, their quality plain to see.

“Good selection here, owner. You’ve even got blood swallows’ nests.”

Blood swallows’ nests were notoriously rare and commanded extraordinary prices.

The owner smiled. “They’re not easy to come by. You have to go deep into cave systems — pitch dark inside, full of treacherous currents and venomous snakes. Many people have lost their lives trying to gather them. We only have five in stock. They’re very precious.”

“Do you handle the harvesting as well?” Shi Ting asked.

“We have a few workers who collect for us, and we also buy from other collectors.”

“Could you bring out the workers’ tools for us to have a look?”

“Of course — one moment.” The owner disappeared into the back room and returned with a tool bag. Inside were an assortment of implements.

“There it is.” Shi Ting’s eyes sharpened. He reached in and drew out an axe — one that differed from an ordinary axe in that its handle was considerably longer, with a hooked spike at the opposite end, honed to a sharp edge.

“That’s a mountaineering axe,” the owner explained. “All the bird’s nest collectors use them.”

“Owner, would it be possible to borrow this? I’ll return it.”

“Certainly, certainly.” The owner nodded without hesitation.

Shi Ting had Bai Jin secure the axe, then turned back to the owner. “Among your workers — does any one of them have a history of psychiatric illness?”

“None at all,” the owner said with certainty. “I handpick all of them. Sharp-minded, able-bodied.”

“And among the independent collectors who sell to you — do any of them have a history of psychiatric illness?”

The owner considered this. “Now that you ask, there is one who comes to mind.”

Shi Ting and Bai Jin exchanged a glance. There was something here.

“His surname is Hu — in his twenties. People call him Hu Er. His father spent his whole life gathering bird’s nests. Three years ago the old man was bitten by a venomous snake and died trying to collect blood swallows’ nests. Hu Er had been working alongside his father, but after the old man died he came around less and less. A year ago he told me he was going home to recover from an illness, and I never saw him again.”

“How do you know he has a psychiatric condition?”

“He had an episode here in the shop. He got into an argument with one of my staff over the price of bird’s nests and ended up rolling around on the floor, making a scene, saying all manner of strange things. My staff mentioned that he’d suffered some kind of shock as a child and was not right in the head.”

“Do you know where this Hu Er lives? Does he have any family?”

“He lives somewhere in the Lucheng district. He has an older brother.”

Shi Ting said quietly, “It all fits.”

After leaving the owner, Shi Ting immediately organized a search operation. After sustained effort, a resident of Xiaosan Hutong in the Lucheng district provided a lead: there was a pair of brothers living in their alley. The younger one had previously earned his living gathering bird’s nests, but had been at home idle since falling ill, supported by the older brother.

With this resident’s help, the group located the brothers’ address without difficulty.

It was an ordinary tiled house. The courtyard was filthy and in disarray. Several scrawny hens clucked about, pecking at the ground.

The group fanned out along the wall and crept toward the entrance.

Shi Hao crouched by the main door and gently drew it open. A foul smell wafted out. A hen squawked and bolted from inside.

Shi Hao released a breath and lowered his gun — a false alarm.

Inside, the smell was even worse, thick enough to turn the stomach. Leftover food sat in a pot on the stove. Chicken droppings were scattered everywhere.

Shi Hao forced himself not to cover his nose.

He pushed open the door on the left side and found a figure lying on the brick bed, curled beneath a ragged quilt whose cotton stuffing had blackened and was spilling out.

The figure was fast asleep, oblivious to the officers’ entry.

“Don’t move.” At Shi Hao’s thunderous shout, the sleeping figure barely had time to react before he was in handcuffs.

The man was powerfully built — like a bull — and even with his hands cuffed, he thrashed and kicked at Shi Hao, emitting shrill, strange sounds from his mouth. It took Shi Hao and three other officers working together to restrain him fully. Shi Hao stuffed a cloth into his mouth to silence the shouting.

At that moment, footsteps approached from outside the main gate, and a voice called into the house: “Er Dang, I’m back.”

—