If you like you can look at the (sketchy, incomplete) GM notes as well.

Burglary

As he paused for a moment before dropping from the window-sill to the ground, he shuddered. The night was warm and there was no cause to shudder save that a twinge of joy, of dark joy can shake the body, when a man is alone, under the moon, on a secret mission, with hunger in his heart and ice in his brain.
- Mervyn Peake, Gormenghast

Burglary in many respects is simple. You need to gain entry somewhere you're not wanted, take something you're not meant to have, and leave without being caught or recognised. The "getting away with it" part is, in many respects, the difficult bit.

Sites in Horizon you may wish to break into will often be secured in some way, and the GMs will assign a descriptor to each such site:

A Wide Open place has next to no security - entering and leaving unseen is a trivially easy matter. A lonely hut in the country, or a filthy shack or tenement apartment in the Slums will fall into these categories - so long as the occupant is away, nobody's looking after the place and nobody's left behind boobytraps.

A Weakly Secure site will have some security, but really not much. We're talking your average townhouse, or an apartment in a building where the landlord is onsite and keeps an eye open for trouble, or a market stall manned by a single inattentive merchant, or a gypsy caravan.

A Moderately Secure site may well have people guarding it on a permanent basis, but they're not likely to be especially tough or competant. Alternately, the major points of entry could be hard to slip into - either because they're locked, hidden, or watched. This is the sort of security you'd expect to get on the more run-down mansions of the Noble Quarter, or the backroom at one of Shoreleave House's establishments, or a market stall run by someone who can afford a guard, or your average shop in the trading district, or the caravan of the leader of a group of gypsies, or unimportant government offices.

A Well-Secured site will definitely have professional, trained guards there. The major points of entry will be secure and guarded. More secure shops in the trading district will have this sort of level of security, as will heavily-guarded merchant's stalls, important government offices, and the mansions of well-off nobles.

A Stronghold will have frequent guard patrols, few guarded points of entry, and the Watchdogs are liable to check it on their patrols due to its nature. Banks tend to have this level of security, as do the most secure mansions of the Noble Quarter.

An Airtight location has the best possible security. We're talking Embassy-secure, Colonel Zero's rooms in the Imperial Palace-secure, or "nobleman's virgin daughter's bedroom"-secure. A great many patrols, guardposts incorporated into the architecture, bright shadowless corridors leading into secure areas that are watched constantly, checkpoints which require passwords and identifications and whatnot required to pass... the works.

The above categories merely describe how secure a location is - how difficult it is to sneak in and out of a particular place without being seen. There may be other in-character difficulties which could foil a burglary attempt. The valuables you are looking for may be kept in a safe or vault which will require either a prolonged period of safecracking or a very loud explosion to open.

It should be noted that it's often difficult and expensive - and indeed will often be impossible - to make large areas Strongholds or Airtight locations. These two ranks will often only apply to specific areas of larger locations. For example, the less critical parts of the Imperial Palace are only Well-Secured, because it would simply not be feasible to make the entire place Airtight; however, many important locations (such as the parts where Colonel Zero lives and works) are Airtight.

How It Works

Firstly, we look at your Stealth skill. All else being equal...

...an Averagely stealthy individual will be able to get away with sneaking in and out of Wide Open places.
...a Quiet person can slip in and out of Weakly Secure sites.
...an Infiltrator can, well, infiltrate Moderately Secure locations.
...a Master Thief can break into Well-Secured sites.

Someone who is Obvious will not even be able to sneak into Wide Open places unless they can swing things to their advantage!

If there is a group of people attempting to break into the place, the Stealth skill of the group will be equal to the lowest Stealth skill possessed by the characters present.

Example: Louis, who is a Master Thief, and Bruno, who has the "Stealth: Obvious" disadvantage, are going to try and break into Lord Fortescue's mansion. Lord Fortescue's mansion is Well-Secured. Were Louis on his own, the mansion would be no problem, but alas the oafish Bruno is spoiling everything with his clumsiness, and the Stealth rating of the duo is Obvious. This is why Master Thieves like to work alone.

Secondly, we take a look at pre-existing factors which could increase or decrease your chances, and we will adjust the difficulty accordingly. We will list the factors and decide which are Major Advantages, which are Minor Advantages, which are Minor Disadvantages and which are Major Disadvantages. Here are non-exhaustive lists of examples of each:

Major Advantages: Someone helping you on the inside who has a degree of authority within the location concerned (the chief guard or the head butler, for example). A map in your possession of the exact layout of the location, with security features noted down. The security measures are in disarray - perhaps the guards haven't been paid for a week and are resigning in droves. Three Minor Advantages.

Minor Advantages: Someone is helping you on the inside, but they are limited in the ways they can help you (they might be a stableboy, for example, or a disgruntled chef). You have a sketchy map of the location, but it doesn't show everything. The security measures are relaxed for some reason - perhaps the usual guards are having their day off and inexperienced reserves are manning their posts.

Minor Disadvantages: The guards have had word that something dodgy is going to happen but aren't sure what it is, or when it's going to happen. You were expecting someone on the inside to help you and planned accordingly, but they've chickened out for fear of the Doghouse and won't help you now. You're using an inaccurate or out-of-date map. You have to spend a while picking open a lock.

Major Disadvantages: The guards know that you are coming, and have a fair idea of when you're going to show up and what your plan is. Your plan depends on inside help from someone who actually intends to betray you and set a trap for you. You are using an outrageously fake map. You have to spend a while letting a safecracker open a safe or vault. You have to make a loud noise forcing open a locked door or chest because you have nobody with the Pick Locks skill available. Three Minor Disadvantages. (Note: If you have to use explosives to blow open a safe or vault because your party lacks the Safecracker skill, this counts as TWO Major Disadvantages.)

Your plan in turnsheeting will have a major effect on this. We will look over your plan for breaking into the location carefully - it is in your interest to create Major and Minor Advantages for yourself. Perhaps the vaults of Lord Fortescue's mansion are an Airtight location, but the kitchens of the mansion are merely Well-Secured - a Master Thief could sneak into the kitchens, poison the food for the vault-guards, and hence reduce the security level of the vaults significantly (creating a Major Advantage).

We will then enumerate the various advantages and disadvantages. Major Disadvantages cancel out Major Advantages (or three Minor Advantages if there are no Major Advantages) and vice versa; similarly, Minor Disadvantages will cancel out Minor Advantages (or turn a Major Advantage into two Minor Advantages if there are no Minor Advantages) and the converse applies. If, at the end, you have one or more Minor Advantages, the effective security level of the location is reduced by one. If you have one or more Major Advantages (or three or more Minors) the effective security level is reduced by two. If you have three or more Major Advantages (or nine or more Minor Advantages), the effective security level is reduced by three. If you're left with disadvantages, the security level will be heightened accordingly.

Lastly, because sneaking into a location is always going to have some risk, we'll roll one of our trusty six-sided dice. If we roll a 6, some twist of fate has made life easier for you and the security level is decreased by one. If we roll a 1, ill luck has come your way, and we will increase the security level by one. And laugh and laugh and laugh.

Once this final adjustment has been made, we will compare the Stealth skill level of your party with the adjusted security level (and yes, the security level can end up being adjusted below Wide Open or above Airtight if things go especially well or catatrophically badly). If the adjusted security level is equal to or less than the highest security level someone of your Stealth skill can handle, your burglary is successful. We'll get you next time, Gadget. Next time.

It's a lot more entertaining when the security level exceeds your capabilities. If it merely exceeds your capabilities by one or two levels, you have managed to evade capture but you were seen by the guards, you didn't achieve whatever you were sneaking in there to achieve, and there may be evidence left behind to link you to the break-in. Better keep an eye out, or it'll be the Doghouse or the bottom of the river for you.

If the security level exceeds your capabilities by three levels, then it's Roger Me Spinally time; you've been captured, and something bad will almost certainly happen. You may be able to bargain your way out of being sent to the Doghouse for the time being - but should you do so (and we don't guarantee that you'll always get the opportunity) you'll be heavily indebted to someone. With hilarious consequences!

Securing a Location