Mosaic City, located along China's coast, is quite large city sometimes called the Crossroads Between Nations due to its diverse population. While it was once a large tourist spot, the city was placed under a blockade as the military appeared claiming there was a radiation leak. The true hazard, however, is much more sinister.
Here is where you'll find the rules for P:SP, as well as a bit of basic info on the setting on the P:SP. It probably goes without saying that coming here is one of the first things you should do if you're thinking of joining.