is this plausible?

Foreign assassins come into a city with the task of murdering their king. They buy a map of the palace, but it turns out that the obe who sold it has an understanding with the crown and reported them.

Does this situation sound plausible to you, or just a deus ex machina?

Fairly. Especially of the crown is somewhat totalarian and has a Secret Police / State Sec with informants everywhere.

I have more trouble imagining a shop-keeper having a connection to the palace than I do him reporting it, but even that's probably not too far-fetched, maybe the shop-keeper was once a soldier, but was wounded in battle and had to retire, while a friend also retired but ended up in the palace guard?

The shopkeeper has ties with the Secret Police network. Seriously, it happens in North Korea now & it happened all over the place in Stalinist Russia.

Besides, simply not verifrying the validity of their source/contact makes those assassins look like amateurs. While falling into a trap made to catch spies & dissenters makes more sense.

Presumably the "understanding" isn't directly with the king but rather with somebody else in a position of authority. Say, the people in charge of tolls, tariffs and taxes, who occasionally look the other way in return for information on bigger offenders.

Many medieval cities had a lot of tariffs and fees on goods brought to market there (or just passing through), and that was in fact one of the main sources of revenue. It follows that most of them also had smugglers. A certain amount of smuggling can be considered unavoidable, but it's a bad idea to let it go too far, so a wise ruler would have some people on their payroll keeping an eye out for such things.

As mentioned, situations like that happen all the time in more totalitarian regimes.

And even in some non-totalitarian ones. Just take a look at the bombing of the Rainbow Warrior.

It's certainly plausible that your assassins could obtain a map of the palace. It would not be plausible for them to purchase such an object off a random shopkeeper. No absolute ruler would ever allow such a map to published, as it would deeply compromise the security of their home.

However, there would probably be maps of the building somewhere, as the place must have been built following some kind of plan. If the palace is a relatively recent construction, the architects who built it might still be around. The assassins could get in touch with them, and bribe, blackmail, or otherwise coerce them into handing over the original design documents. Or if the palace is ancient and the architects are long dead, those plans might be found in a local library or other record-keeping office. Again, blackmail, bribery, or suchlike would all work here.

Alternatively, the assassins could find someone in the palace staff with suitably flexible loyalties, and get them to draw up a map based on first-hand experience. It wouldn't be as accurate as the architectural plans, but it could hold details that would be missing from the plans, like the decor of certain rooms or their specific contents. The contact could be anyone: a disgruntled guard, a young maid who's gotten in the family way, a nobleman with a scandalous secret... all that matters is that they have something the assassins can use as leverage.

Then, when the assassins get their map and move on to planning their attack, whoever their contact was could just rat them out. If they bribed someone, maybe their bribee pocketed the money and went straight to the king to name names. Or, maybe they got greedy and hoped to double their profits, by confessing to the king and being rewarded for their loyalty. If the assassins blackmailed or coerced their informant, maybe they went to the king and begged for mercy and protection. Or maybe they resented being manipulated, and snitched out of spite.

Any of these scenarios would be completely believable, and you wouldn't have to come up with a bizarre "all the shopkeepers are KGB informants" explanation to make them work.

edited 14th Sep '14 3:20:42 AM by Tungsten74

It is however fairly credible for the group to stumble upon a shady shopkeeper (maybe a famous black market trader or some such) who has a map of the palace aided by some proof that it is legitimate (such as the Royal Seal at the bottom of the map or some such).

It's in fact a pretty classic thing in fantasy. Group of adventurers (or in this case, Assassins) arrive in town looking for some quest, some black market guild or merchant hears about it and approaches them with what they need. In which case the set-up outlined by the OP is a Subversion or perhaps Deconstruction (depending on how far he goes with it) of the concept.

I question the judgement of a black market dealer who rats out his clientele to the authorities. Sounds like a good way to ruin your reputation and lose all your business.

edited 17th Sep '14 5:29:53 PM by Tungsten74

This sounds like something off of the Evil Overlord list...

Step 1: Provide all seedy-looking sources of information in the city with fake maps and promise them a decent reward (enough to make it worth their while, but not so much that it's a viable source of income!) if anyone actually tries to use them.

Step 2: Dole out the reward when someone actually tries to use said fake maps. (Either alter the maps for each source, or have the source come forward after the sale but before the incident can occur. No payments unless someone gets caught in a trap!)

Step 3: ???

Step 4: No profit, but you do get to live a bit longer.

Sounds plausible to me.

Or you could, y'know, not rely on tired fantasy clichés.

In what way?

I was going to make a big post explaining myself, but the more I read over what I wrote, the more I realised I was just starting an argument for no good reason. The OP got their answer ages ago - they're probably snitching out assassins with two-faced fences right now, as I type. So I'm just gonna bow out and let this die. Forget I said anything.

If you wish to explain your perspective, I have no problem in reading. It'd be good as feedback :D

As for the poor assassins, they have indeed been imprisoned and are now awaiting interrogation :P

Thanks to everyone for your replies, they have been very helpful!

Did the map turn out to be real? If he sold them a fake map, most of the objections go away...

If they get their map from a black market dealer, the dealer in question could simply have been captured by the authorities and forced to tell them what he's been selling, including the map. Way more plausible than him willfully betraying his own customers and losing all credibility.