Did China's 59-year-old president-in-waiting, Xi Jinping, put his back out playing sport? Or did a common cold force Mr Xi to cancel meetings last week in Beijing with the US Secretary of State, Hillary Clinton, and Singapore's Prime Minister, Lee Hsien Loong?
Or is there something even more sinister afoot? Everyone in Beijing is asking, where is Xi Jinping? Overseas Chinese websites and domestic bulletin boards became even more restive when a meeting between Mr Xi and Danish Prime Minister Helle Thorning-Schmidt was cancelled. Officials said the meeting was never scheduled.
This kind of cancellation is extremely unusual, especially at a time of great sensitivity like now, just before the 18th Party Congress next month, which is supposed to start the transition of power to the Xi era. So intense is the secrecy, we don't even know for sure when the transition will take place, and Mr Xi has never been formally named as successor.
"Barring Xi offering a very unlikely explanation about his cancelled meetings last week, the outside world may never know the exact reason, and the rumours are unlikely to fade away," Wang Xiangwei, editor-in-chief of Hong Kong's South China Morning Post, wrote in a commentary.
In the absence of real information, China is rife with rumour about the movements among the political elite.
Economic data this week has shown the Chinese economy is slowing significantly, adding to the overall sense of insecurity. The US-based website Boxun.com claimed Mr Xi had been injured in attempted revenge plot by supporters of purged former party high-flyer Bo Xilai.