Bran Blackbyrd said:
OK.
I have incriminating pictures of you. Post an adventure and no one has to see them.
Okily dokily.
I have an idea - it's just a sketch of course. You'll notice lots of square brackets.
The players are hired by [an organization they trust] to retrieve [something important for some reason] from [some nondescript bad guys] like an crooked corporation. This could include a weapon, a jamming system, something that will detect stealth aircraft, or if you really want to it could be something extraterrestrial or FX.
Unfortunately [organization that nurses a grudge] is aware of this (perhaps through a mole) and intend to not only take the [object] but to prevent the heroes from acquiring this technology.
They can sabotage the mission somehow (blow up their yacht, hire mercenaries who don't know who they are, etc) before the heroes can get to their destination.
(Imagine if the players take an airplane there, and none of them has the Pilot skill so they just go through an airport. The villains could steal their luggage, get them in trouble with Immigration, find a way to delay the flight such as firing a rocket at another plane, or put a hijacker onboard the airplane.)
The heroes should prevail without knowing who these mysterious adversaries are and get to their destination. Once there they have to break in, get the object, and get out without getting filled with lead (anything preventing slimy corporate guards from using hollowpoint or explosive bullets?).
(To add a twist, perhaps the evil corporation's lead researcher didn't want his object to be used for war, and wants to defect with the heroes. Now they have to drag a frightened non-combatant with them... heh heh heh. Or maybe he's just lying, and back-stabs them. Or maybe they find his corpse.)
Unfortunately for the players, as soon as they get inside [organization that nurses a grudge] come in shortly afterwards, and, uninjured, with most of their bullets, and without the need to over-ride security procedures like that annoying electric floor the GM sic'd on his players and that door that simply refused to open without the aid of explosives, order the heroes to surrender.
Now the heroes have a choice: should they surrender the object? These guys bear a grudge, so maybe they'll just get shot afterwards. Should they run for it? How about shooting their way out? What is that wimpy scientist doing - cringing, pulling out a syringe with paralytic poison?
Then the victorious (?) heroes return to their employers, hopefully with the [object] undamaged in tow.
You can also change "alignments" - the guys with a grudge could be the FBI if the "heroes" have frequent run-ins with the law, and the evil corporation can still be evil, or good, if you prefer.
The best part is this adventure can be quite short. You just need stats for the [saboteurs], the grudgies (the leader and his minions) and the corporate security guards (or military lab, or whatever). And maybe the scientist, if you didn't off him.