I'm a fairly new GM and stick mostly to canned adventures, but I have an idea for a session that I think would be fun, but I need help really fleshing out the story.

Basically I want to do the Hang Over. My idea is to have the PC's (4 of them, including a droid) wake up in a room in a limited environment (maybe a very small island with a space sport, cantina, hotel, few warehouses etc... Any other location I may need that serves as a loading/shipping base for a larger settlement that doesn't all off-worlders......) with no memory of the night before. I'd populate the town with a few NPC's who have info for them, and it'd be up to them to find out follow and sort out the info they are told and piece together what happened and solve some issue.

The problem is I'm not sure what 1) Happened the day/night before to them and 2) what clues I should give them up front.

Basically I have an idea and concept, but no idea what the actual story should be.

You know your players better than anyone else does so that's a tough question to answer. Are you familiar with gnomestew,com? They put out a book called Eureka: 501 Adventure Plots to Inspire Game Masters that's available (I think) on Amazon as a paperback or on DriveThruRPG. That would be my first suggestion.

When creating clues, you're essentially taking out-of-context snippets of your plot and scattering them around out of order. When you figure out what the plot is (see paragraph above), chop it up, and have the PCs find pieces either at random or a pre-set locations.

The structure and splitting up the clue etc... I don't think I'll have a problem, my problem is coming up the story (ie - what they did the day and night before) without making it a Hangover rip off.

Again, that's where a book (or some other source) of quasi-generic plots would really help you out. File off the serial numbers, paint it in Star Wars colors, and you're good to go.

There are lots of sites like rpglibrary.org that can be a good source. See also TVtropes.org if you're not afraid to lose your mind in that rabbit hole.

I rarely develop any story whole-cloth. It's a game, not something I'm putting to publication.

One thing you could do is NOT decide what actually happened. Players talk a lot at the table, let their paranoia and wild guesses, as well as actions in-game, decide what actually happened. Have some ideas, of course, and an overall direction, but let them flesh out the details. I've changed many a plot at the last second because a player unwittingly gave me a better (or worse, mwa-ha-ha!) idea mid-game.

Mind you, it might help if we knew what characters we were brainstorming for. What's their backstory? But as for just firing randomly in the dark, we could go in a couple of directions with this.

How about - they have a job they agreed to while blacked out. Now they have to ship 400 tons of manure to Tatooine, but first they have to liberate the cargo from the storage depot. All they have to go on is a pile of credits and a thanks for taking the job! note.

Somebody got married? "Sorry M'am, I had no idea that we were in the Chapel O' Love last night!" "But honey! You said that we'd be together forever! *WAAAAAH!*"

Oooh, even better - make the betrothed a con man who's winding the character up. They saw someone in an incapacitated state, saw a perfect patsy for a job that needed doing, and took advantage by fabricating a wedding.

More sinister and serious - they wake up covered in blood. Perhaps the cops are looking for them for something they actually did? Perhaps it's just a frame job?

There was a Traveller version of this where the "Patron" hired the group to perform a mission and in return had to undergo a mind wipe to protect their business interests.

A message was left which was left obscure except I promptly figured out what it meant since it seemed like we had been about to accept the mission rather than immediately after.

There was also an actual play via the people at Order 66 podcast where they started with their group coming to inside a Black Sun Vault with no idea what was going on in fact they didn't even remember who they are!

I think they're still planning the third part of that particular actual play.

As for ideas, what are their obligations?

Have they stumbled onto a hidden gas cylinder and got exposed to something that removes some of their short time memory like the actual play... could even have an artefact be the cause except whilst they were unconscious someone has walked off with it and eventually when they figure out its missing have to recover it to complete their mission and recover their ship currently impounded until they return with the artefact.

What if they were slipped a mickey?

What do they have that someone would sedate them to acquire?

Has someone stolen their identity and does this mean people will remember them even if they don't...

Building off the theory that the players will help you make a story (whether they know it or not), you could also turn it into some kind of horror/suspense story...

If you've ever seen the SciFi channel movie "The Cube" (terrible movie, intersting idea) or the more recent Joss Whedon / Drew Goddard movie "Cabin in the Woods" (campy but entertaining) you could have something like that (though less violent/deadly)

While on a job in a skeezy back-ally cantina, the PCs were drugged/rendered unconscious by some means and wake up in a location they don't recognize at all.
-or-
Congratulations! You've won an all-expenses paid trip to this lovely isolated Island resort! [...where noting is as it seems ]... funny though, you don't remember entering a contest.

There's a "puppet master" type big guy pulling strings in this movie set style town and all the NPCs there (if there are any) are actually actors (or to follow a darker theme - cult followers).

It's all part of some crazy reality tv-esqe show which the PCs don't know about. The PCs have to find certain clues/solve certain puzzles to get out of the town/off the island while there's all sorts of chaos or shenanigans happening about (wasn't there a guy standing RIGHT THERE two seconds ago?! ...why is it every morning we wake up, there seems to be fewer and fewer people in this town? ...WHERE DID THE BOAT GO!?)

Or they're supposed to be the sacrificial lambs to this psychotic group that follows this ritual of letting their victims wander into traps.

Sorry if that's a bit more dark/depressing than you're going for, I'm just better with suspense than humor. The biggest problem I would have with making it more comical like with the Hangover where they were out doing shenanigans the night before is the Droid - they're immune to drugging >.<

Here would be my attempt at more commic-y...
Think something like Oceans 12 (or 13) meets Hangover
they were hired to do a heist of [some item].
In the process of completing this heist, they had to hire help. Said help included a cat burglar Squib that makes ADHD children look calm; a male Twi'lek grifter (who was disguised as a female); and a Kowakian monkey-lizard that really likes being around them but won't stop cackling.
Upon completion of the theft, a rival thief (or group) came in and stole [the item] from them while simultaneously drugging/knocking them out/wiping their short term memories and dumping them where they're sure to be found either by the authorities (who still aren't certain who stole [the item]) or the big guy that hired them to steal [the item]. Fortunately, they woke up just before that and were able to get out of the immediate area.
After shenanigans ensue trying to figure out what happened, they end up piecing it all together to find the squib had already swapped the real [item] with a fake, stuck it in the twi'lek's purse and let the second thief(s) steal a fake (so they've had [the item] the whole time )

Congratulations! You've won an all-expenses paid trip to this lovely isolated Island resort! [...where noting is as it seems ]... funny though, you don't remember entering a contest.

There's a "puppet master" type big guy pulling strings in this movie set style town and all the NPCs there (if there are any) are actually actors (or to follow a darker theme - cult followers).

It's all part of some crazy reality tv-esqe show which the PCs don't know about. The PCs have to find certain clues/solve certain puzzles to get out of the town/off the island while there's all sorts of chaos or shenanigans happening about (wasn't there a guy standing RIGHT THERE two seconds ago?! ...why is it every morning we wake up, there seems to be fewer and fewer people in this town? ...WHERE DID THE BOAT GO!?)

Oh man, that's brilliant! If you're going go with the top shelf mindfuckery, you might as well steal from the best:

I would totally shamelessly steal every last episode of that show for a game - if only 50% of my players wouldnt instantly know what I was up too. (Well, that and I'd never be able to do it justice).

What if they were shipping some sort of knockout gas that affects short term memory? :-)

What if the droid was in on it and had been told by the rest of the party to not tell them what happened to the point of either adding a part that would wipe that part of its memory as a deterrent?

What if your party willingly had their minds wiped?

Now what kind of game could you run where that revelation would stun your players?

Off the top of my head I'd have them be part of an expedition to an Outer Rim world that has been impounded maybe by the Empire but the reason they were sent in was because something or someone effectively disappeared an entire Imperial starship and crew with no sign of what happened to them.

Now the first time the players didn't know that they turned up went down to the planet found an unfinished temple above a tomb with a sealed mine entrance hidden out of view at the back of the temple.

Naturally the expedition broke open the seal on the mine and thats when things went downhill.

My idea is that something was sealed inside the mine for some long forgotten crime and when released it infected everyone present at the opening and who also went inside.

By the time of the start of the adventure they learned it was an ancient Sith Spirit which would eventually possess each of them as long as they retained anything about their trip to that world... assuming it included memories they wittingly dumped everything and fled the world until they could arrange to have their minds wiped and placed the device in the droid in case they got curious so it could prevent them repeating their mistake as it couldn't be possessed...

Unfortunately...

Edit: I believe that was a Torchwood episode that inspired that idea, but I had thought about it turning into a sequel where your players discover more about the past of that Sith Spirit and learn how to exorcise it permanently so they could loot its tomb without fear... well from it at least!

Have a recurring enemy making use of various artefacts looted but unaware wearing it got them possessed so you have arcs where your players learn the exposure was merely a form of compulsion and that it was wearing one of its artefacts is what got them possessed (now I'm pillaging Harry Potter!)

How many games have you played where your players had to save the villain because killing him/her meant it would possess one of them?

Edit: I believe that was a Torchwood episode that inspired that idea, but I had thought about it turning into a sequel where your players discover more about the past of that Sith Spirit and learn how to exorcise it permanently so they could loot its tomb without fear... well from it at least!

There was a Torchwood episode kind of sorta like that, but it sounds closer to the Red Dwarf episode Thanks for the Memory from season 3.

Edit: I believe that was a Torchwood episode that inspired that idea, but I had thought about it turning into a sequel where your players discover more about the past of that Sith Spirit and learn how to exorcise it permanently so they could loot its tomb without fear... well from it at least!

There was a Torchwood episode kind of sorta like that, but it sounds closer to the Red Dwarf episode Thanks for the Memory from season 3.

Missed that one will have to correct that oversight since it may have been better than the Torchwood episode!

Thanks everyone. Some great ideas, and definately some stuff I think can be added. I do like the Droid knowing but not being able to add anything.

One thing I loved about the Hang Over is how, ultimately, pointless the movie was. They follow these clues, go from the Doctor to the Chaple, to the Stripers, to Mike Tysons. Have a police car and get involved with a gangster, when all they had to do was go up on the roof, and they even had a clue as soon as they step out of the hotel.

I think I need to work it backwards, come up with the story (why the group is on this planet and what they do), and then split that story and info up in the "Hang Over" frame work. I'm just having trouble coming up with that story.

I think the knock-out gas shipment idea is one of those things you have a clue of it there (if they check their ships manifest or something) but is something they may not think of doing. And it explains the memory loss without having them haved partied (so I don't have to work that in). Now its just getting that hook to start the story off (ie - whats their "missing friend").