It flashed across Yu’s mind that Peng, the first victim, had been attacked on her way from a hospital. She could have got that yellowish mask from there.

Standing outside the store, Detective Yu immediately started making inquiries with a list of hospital phone numbers Baidued on his cellphone.

Not exactly to his surprise, Shanghai Number One People’s Hospital, the first one he contacted, confirmed that the yellowish masks had been ordered and supplied for free to staff members and in-house patients, and to the family members accompanying the patients there too. With the smoggy air, even healthy people were prone to flus, and the hospitals were particularly concerned with cross infection for the patients with low immune systems under chemotherapy.

So it was not too surprising for Peng to have a yellowish mask for herself, even though she was not really a hospital staff member.

But if that were the case, what about the third victim, and possibly the fourth? They too had the yellowish masks – possibly planted beside them.

Inspector Chen arrived at the south entrance of the New World.

He checked his watch. Still about twenty minutes before the meeting at the Oriental Club. He took a walk around the area first, pulling his gray felt beret lower, and adjusting a pair of amber-colored glasses along his nose ridge.

The Oriental was a club for the successful elite in the high-end area of the city. Chen happened to know about the place through Mr Gu, the developer, who had pushed into the inspector’s hand a club membership card for free – ‘in recognition of your excellent translation of the business plan, which succeeded in securing the first international loan for the New World’.

He did not see anything unusual after circling the club a couple of times.

At the club entrance stood an elderly doorman in a red uniform, smiling, bowing, who stopped Chen with his white-gloved hand raised.

‘Mr Bian of the Air Product Group is sending me here as his representative,’ Chen said, producing his membership card as well for something like double insurance, ‘for the meeting at twelve thirty.’

‘Another representative,’ the doorman mumbled, casting a curious look at Chen’s amber-colored glasses and waving him in without further ado.

On the first floor of the club Chen found a spacious meeting room arranged like a lecture room with a lectern and screen at the front, and rows of leather-cushioned chairs for the audience.

The room was already in semi-darkness, with the windows closed and the curtains drawn, and quite a number of people sitting in there. Chen moved to seat himself at a corner in the back, surprised at the large turnout. Thirty-five or so, possibly more by the time the meeting began. Luckily, they seemed not to be interested in making small talk with each other. Rather, they appeared to be quite cautious, saying little to each other, and none to an unfamiliar face like Chen. They knew they were going to watch a movie soon.