Shortly afterward, both of them got off at the New World station.

It was getting even weirder. The New World was a high-end shopping complex for the successful elite in the city. Yu had had coffee with Inspector Chen here the day before. It was too early, however, for shoppers and visitors.

Why should the jogger – if that was what Lou was, after all – have come all this way, taking one subway train and changing to another, to the New World? It did not make any sense. The New World was, if anything, not an area for jogging.

But the man was turning into a jogger once again, slower now, more like one walking at a relatively quick pace. He was obviously up to something, but it was already past six twenty.

For a plausible scenario, Yu thought frantically, the man was out there for reconnaissance. Today might not necessarily be the day. The murderer had to familiarize himself with the surroundings first. That was probably why he did not have to worry about the established time pattern.

And the choice of the New World, another central location of the city, made sense too. Historically, it was in one of the shikumen houses here that the Chinese Communist Party had held its first national conference. After the first four cases in other central locations, the New World certainly made a justifiable spot.

Jogging on, the man seemed to suddenly quicken his steps and move close to a middle-aged man in front, dangerously close, but instead of making any attempt, he turned away, and several minutes later, closed in on an elderly woman with a limp. Still, he did not try to do anything.

People were beginning to show up in the New World. The lights of the Starbucks at its north entrance turned on, almost time for the arrival of its earliest customers.

The man was turning round again and retracing his steps to the Line 10.

Yu moved behind at a cautious distance until the man disappeared into the crowd at the subway station.

At least there was no time for him to strike out that morning. Too late. It was already six twenty. A serial murderer would have closely followed the established time pattern.

There were a lot of things still beyond the detective, but he thought that the murderer would come back to the New World the next day. And most likely much earlier.

Chen was awoken by a shrill sound, like a cricket moaning in the first chilly wind of the fall. It turned out to be the ringing of that special cellphone of his.

Rubbing his eyes, he saw the light streaming in through the window. It was seven twenty-five. There appeared a weird text message on the phone screen:

‘Another monstrous live turtle for two of us there. Eleven o’clock.’

The message came from Melong, who was moving quickly. And cautiously, too.

For a notorious gourmet like Chen, an invitation to a turtle meal – even if the message was intercepted – would not have sounded suspicious.