OUT OF THE BLUE, the Shanghai Police Bureau got a tip.

The tip-if that it was-came in the Shanghai Evening News. To be exact, in a classified ad clipped from the newspaper and mailed to the bureau, in an envelope addressed to Inspector Liao:

LET’S GET THROUGH the three-accompanying. After the singing and eating, it’s time for dancing. As for the place, which is better than at the Joy Gate? The usual time, you know.-Wenge Hongqi

It could have been a humorous message among friends. But the message, when addressed and delivered to Liao, turned sinister.

“It’s not a tip,” Liao said, frowning.

Among the red mandarin dress victims, one was an eating girl, and another, a singing girl, so the next should be, as Hong had suggested, a dancing girl.

“The usual time” sounded even more urgent. Thursday night, or early Friday morning.

“Wenge Hongqi” was evidently not a real name. It could be interpreted as “red flag in the Cultural Revolution”-an unlikely nickname for anyone in the nineties.

“Red flag in the Cultural Revolution,” Yu said. “Sounds like the name of a rebel organization from those years.”

“Hold on,” Liao said. “Hongqi also sounds the same as the first two syllables in hongqipao-red mandarin dress.”

Liao lost no time getting in touch with the newspaper. The editor maintained that he hadn’t seen anything improper with the ad. It had been paid for in cash and delivered to the editorial office through “quick delivery,” one of the newest services in the city, which anyone could start up with a bike or a motorcar, and possibly without a license. There was no way of tracking down the quick-delivery company. The man who wrote the ad left no address or phone number. It was not required in the case of cash payment.

It was an unmistakable message from the murderer. An unbearable challenge too.

He was going on with his killing, in spite of all the police efforts. Furthermore, he told the cops when it would happen, and where too.

Soon information about the Joy Gate came in. The dance hall was in a six-story building located on Huashan Road, close to Nanjing Road. It had a proud history-in the glittering thirties, the rich and fashionable from all over the city flocked to its dance floor. After 1949, however, social dance had been banned as an attribute of a bourgeois and decadent lifestyle. The building was turned into a movie theater; as such it survived the Cultural Revolution, during which the name of the Joy Gate was nearly forgotten but for one incident. Its huge neon sign of dancing English letters, long unlit and broken, fell and killed a pedestrian walking underneath. The incident was then declared as symbolic of the end of an age. In the early nineties, however, Joy Gate was rediscovered in the collective nostalgia of the city. A Taiwan businessman launched a large-scale renovation of the building’s bygone glories, keeping everything the same as it was in the thirties. Time-yellowed posters and decoration were unearthed, old band members reengaged, rusty lighting fixtures and chandeliers refurbished, and the dancing girls, young and pretty, came back, wearing mandarin dresses.

In short, business was booming there again. In the Shanghai tourist guidebooks, the Joy Gate was one of the must-see attractions.

Yu and Liao looked at each other. There was no choice left to them. Hong had been working the case as a decoy-and now the perfect situation for it had arisen.

Yu still had his reservations about the decoy approach. But his colleagues had pressed for it. As the Chinese proverb went, when one was desperately sick, one would seek help from any quack. So Hong had been visiting one nightclub after another, dressed like a butterfly, flipping, flashing, flirting. A considerable number of clients had approached her, according to her reports, but none of them proved to be really suspicious. In order not to alarm the real one, she had to humor them all until the last minute. Her reports didn’t mention, understandably, how much she had to put up with from those lecherous customers.

Now the situation was different.

“He is a devilish one,” Yu said simply.

“She’s been with us for about two years. Well-trained in the academy and with us,” Liao murmured, as if trying to pump confidence into his voice before dialing Hong’s extension. “A clever, capable girl.”

Though Yu didn’t know Hong that well, he thought highly of her. Sharp, down to earth, and dedicated to her job. That was quite a lot to say about a young cop. The homicide squad had come under too much pressure, and Liao’s decision was understandable.

“This could also be a fake move,” Yu said. “If we put our people at the Joy Gate, he may strike somewhere else.”

Liao nodded without responding immediately, as Party Secretary Li was striding into the office, panting, and declaring in a strident voice, “That’s too much. You have to stop him. Our whole bureau is behind you. Tell me how many people you need, and you will have them.”

Hong, too, came into the office. She took a seat opposite, her hands crossed in her lap. She was outfitted like a “girl,” in a dress with thin straps and high slits. She didn’t use any makeup, her face clear and serene in the morning light.

“I want you to understand that this is voluntary,” Liao started, pushing the newspaper clipping across the desk. “Unlike what you’ve been doing, this is not an assignment. You can say no. Still, you are the one best qualified for the job.”

She took a look at the clipping, pushed the hair off her forehead, and nodded, her black bangs swinging softly over her arched eyebrows.

“If you go to the Joy Gate tonight,” Liao went on, “we’ll be there too. You just let us know the moment he approaches you.”

“How can I tell if it’s him? Those men all play pretty much the same tricks with a girl.”

“I don’t think he’ll try to do anything to you inside the club. He has to get you outside. Once he makes such a move, we’ll stop him. We will be prepared for any possible situation.”

But there was only half a day to get ready, Yu thought. The cops couldn’t really prepare for anything. Perhaps Hong alone had no problem with her role-thanks to her earlier decoy experience.

“Let’s do it,” Li said. “I’ll stay in the office tonight. You keep me informed throughout.”

So they were going to the Joy Gate. Hong took a taxi home to change for the night. Yu and Liao took a minivan with “Heating and Cooling Service” painted on one side, which would serve as a field office. Several cops would soon join them there.

Since the murderer might be connected with people at the Joy Gate, they decided to walk in without revealing their identity and look around like ordinary visitors.

According to a colorful brochure Yu picked up at the entrance, the first three floors of the building were exclusively for dancing, consisting of ballrooms of different sizes and services in terms of “male and female dancing partners,” all at different prices too. In addition to the entrance ticket, there was a so-called fee system that charged by the unit, equivalent to per dance, from 25 to 50 Yuan. That, of course, did not include the tip.

“In addition to those ‘professional dancing partners,’ ” Liao said, “there are also ‘dancing girls,’ who make money not through dancing but mainly through their service afterward.”

It was in the early afternoon, so only the first floor was open for business. The ballroom was lined with tables on both sides and had a stage at the other end. A singer in a florid mandarin dress was performing with a small band. The neon lights produced a nostalgic mirage of money-drunk and gold-charmed dreams. Most of the dancers were middle-aged, and the dancing girls were not too young, either.

“It’s a relatively cheap time period,” Liao said, studying the price list on the brochure.