One thing that normally reassures visitors to totalitarian countries is at least their citizenship means their embassy will be their to help. Unless, of course, your embassy isn't told you're in trouble:

China has released a Chinese-born American university professor who was held for two weeks on espionage charges, the U.S. Embassy said Wednesday, adding to a string of such cases against academics with ties to the United States...Chinese authorities failed to notify U.S. officials of the detention until Aug. 4, a violation of a consular treaty requiring notification within four days, she said. The U.S. government plans to lodge a formal protest with China over that delay and the "harsh and inappropriate treatment" given to Wang, the spokeswoman said.

Just a reminder that China has a nasty side that doesn't much care for diplomatic niceties.