It all started with a taxi. I left my office at about 8pm on Tuesday, waiting for a cab downstairs at the office building, which is near a major intersection. There was heavy traffic and I had to wait about 10 minutes to hail an old Citroen with dark red paint. I sat in the back. The driver, a 30-something man with a distinctive suburban accent, was chatty as most Beijing cabbies are. It wasn't a long journey and the fare was only 10 yuan (HK$11.36). I proffered a 10 yuan note. 'Sorry, it's a bit too new,' the driver murmured. 'I can't take it because I've received three fake banknotes of 10 yuan today,' he added. Poor guy, I thought to myself, before telling him: 'But I don't have any more change.' 'No problem at all,' he said. So I gave him a 100 yuan note, which, I saw, had a corner ripped off. He took a look at it under the dimmed indoor light for a few seconds. 'A corner is ripped off, please give me another one,' he said, returning the note. The second note I gave him was new. He returned it after staring at it against the light for a few seconds, saying: 'Sorry, but it's too new.' I was about to take it back when I saw the serial number of the note began with HD90. It looked exactly the same as a genuine note except that it was a bit too smooth to the touch. The People's Bank of China had released a chart that afternoon identifying the main features of genuine notes amid an influx of counterfeits. I also remembered news reports this week about fake 100 yuan notes with serial numbers starting with HD90. Suspicious, I asked him: 'Is it the same banknote I gave to you?' before taking it from his hand. 'Don't worry then and I'll give you change,' he said immediately. He gave me several 20 yuan notes and I began to inspect them as he watched. It was too dark to see the features that the central bank made public in distinguishing a real note from counterfeits. 'You don't trust me?' he asked. 'I will print you a receipt and please report me if you have any doubts. I thought it was a good idea and took the receipt and left. It wasn't until I got home that I found that the 100 yuan note I had taken back from the driver, with the serial number beginning with HD90, was fake. It still had a corner ripped off and its metal strip was broken. And two of the 20 yuan notes had the same serial number, impossible if they were genuine. I thought I still had a last resort - the receipt. But it was not too hard to tell that it was a fake one under proper lighting - it did not have a proper stamp as genuine ones do and the Chinese characters for 'sample receipt' were printed on it. Then I realised the taxi itself was most probably a fake, too.