Prison is not somewhere you want to end up, infact it's worse then being in the Inferno, because the Inferno can be left at will. Prison is a scene players are transported to if they fail the Bot Test or acquire too many crime points.
Its function is to stop bots and limit pkers, though innocent players often find themselves there.
How do I get out?Edit
Speak to Fir Zhang (44,30) in Prison and either choose "I'm going out", then choose a city, or "I will fight for justice", which pops up a bot test you will then have to complete. If you successfully complete the bot test you will be transported to the centre of Su Zhou. There's an alternate option, "I have amnesty", though it's suspected this is mainly for GMs who end up there by accident.
If Fir Zhang tells you you must wait for a specified amount of time, or you have redressed an injustice today, then you must wait a while before trying to leave. The frequency with which a player visits Prison is noted and adds to the time a player has to wait in Prison, which can be more than 3 hours. The more a player visits Prison, the harder it will get to leave.
If a player finds themselves in Prison due to excessive crime point accumulation, then they must have below 4 crime points before they can leave. Crime points decrease by 1 every hour.
It has been reported that players have gotten stuck in a scene which acts like Prison. This occured because their client closed during a Bot Test. When these players logged in again, they were stuck in the scene they failed the bot test in, with the conditions of being in Prison applied to them (not able to attack monsters, for example).