Level hints: Breakout!
The most imortant thing to know about this level is that there are not one but two prison areas, and two respective staircases and storage areas, A and B. The thieves always start in B block, or at least they always have for me.
Guard strategy
For this map you will want to buy:
Mines
Caltrops
Flares
In addition to your sword/mace and bolts.
At the very start, If your next to block B and want to be evil, throw your mines into the vent . Alternatively, climb in yourself and beat up any thieves you come across.
You will want to rush to two areas early on - the resupply rooms (split into two teams, you wont get both in time alone) and take all the valuable food and items before the thieves can, and then both the staircases as these are the only real way up.
Spam the stairs with caltrops on the dark bits if you want, just have flares ready and listen for footsteps or doors opening. Whistlers may be used, but I think theyre a waste of money on this map.
If the thieves get up the stairs its the usual strategy of search parties - one man with flares surrounded by armed guards, swapping roles as the flares run out. The chest should come out about now, probably in the middle of the hall as this is the most central part of the upper map. Make sure you scout rooms with loot in and relight flares.
Thief strategy
For this map you will want to buy:
lockpicks
invisibility and/or speed potion(s)
In addition to your arrows.
The strategy for this map involves getting into a good position as fast as possible. Quickly get out of the vents, but resist the temptation to hide in the darkness at the exit as crafty guards will expect this. Hurry to the resupply or staircase (depending on the resistance at each - you should see guards moving one way or the other) and then chug a potion and charge up the stairs to level two to grab the key (unless there are no guards, in which case take your time). you can usually ignore the watcher as the guards usually just think some idiot has lowered the gate.
Grab the key, then swig another potion and get to the top of the stairs.
(Sneaky hint - run up the bannister if you can keep your balance, theres less chance of stepping on something unpleasant in the darkness).
At the top youre free to douse torches and darkness hop to pick up loot at your leisure as normal. Just try to stay on the move, or more often than not youll end up surrounded in a small pool of darkness.
Note: this is just one way of tackling the map, intended to stop newbies being slaughtered at the start as they try and find their way out of the cell block. This map is killer on newbies.