Adventure Setup ideas welcome.

[KyleG]

I have two ideas for a first adventure for my campaign

I want the first adventure to be in a old prison (perhaps part of an old temple), within which is trapped in a cell is an old vampire. He isn't the purpose of the adventure but an rp encounter (if released will flee).

What i havent been able to setup is:
why the party is there?
1. How was the vampire captured?
2. Why was he captured and not killed outright - this i am leaning towards they were being experimented on to return them to human.
3. What keeps him here?
It's been several hundred years and he is the sole 'living' occupant in a cell deep within the structures bowels.

The other idea I had was to start with the players deaths.
Led into an ambush maybe and each player drops as part of the opening narrative the last one being killed by a rogue who was part of the party. I have a reason for them rising sometime later (20yrs) but i need help fleshing out an opening adventure.
The basic idea is what do the pcs do after coming back, the obvious answer is seek revenge but the world has moved on and i want to present options for them to do so also. So i need to know some things.
A. Why were the party here?
B. Why were they betrayed?
c. Who were they facing before their demise (because those in the room where they all fell also will rise).
d. where to for the main part of this first adventure?

[Imbalance]

I ran a similar scenario last year. The short of it is that the ruined prison dungeon was from another plane, shunted across dimensions by calamity and stuck underground. Most of the prisoners died of starvation while wardens made their way to the surface. One powerful immortal murderer had been sealed in a pocket dimension, the intact portal hidden by magic. The only other survivor was a hag who later escaped. Years later, she became the party's enemy. Per her manipulations, they went there to try to bargain with her, while she prepared to use them to help unwittingly unleash the evil behind the gate.

[Berenger]

1. How was the vampire captured?
2. Why was he captured and not killed outright - this i am leaning towards they were being experimented on to return them to human.

He turned himself in because they promised to return him to human. Obviously, it didn't work.

[Catullus64]

The other idea I had was to start with the players deaths.
Led into an ambush maybe and each player drops as part of the opening narrative the last one being killed by a rogue who was part of the party. I have a reason for them rising sometime later (20yrs) but i need help fleshing out an opening adventure.
The basic idea is what do the pcs do after coming back, the obvious answer is seek revenge but the world has moved on and i want to present options for them to do so also. So i need to know some things.
A. Why were the party here?
B. Why were they betrayed?
c. Who were they facing before their demise (because those in the room where they all fell also will rise).
d. where to for the main part of this first adventure?

Two people have chimed in on the first scenario, but I find this one much more interesting, so I'll take a crack. The person who betrays them wants a magical artifact hidden in an ancient tomb. He needs help to get it (he's not a particularly powerful Rogue, maybe 2nd level) so he convinces the PCs to come with him, claiming they'll split the treasure. When he betrays them to their deaths (let's say, for example, by triggering a trap that seals them in a chamber and floods it with poison gas, classic villain stuff), his manservant or lackey is also in there with them.

The way to really sell this betrayal is to collude with one of your players. If an NPC says "hey, come into this dungeon full of treasure, I'll split it with you", most players will smell betrayal and be on their guard against this guy. Have one of your PCs play the Rogue, fill him in on what to do and when to launch the betrayal. After they die and wake up again, have the manservant, previously an NPC retainer of the Rogue, be that player's actual PC, who now has a reason to stick with his fellow betrayees.

When they awaken, the first part of the adventure is to escape from the dungeon. Over the past 20 years, passages have shifted or collapsed, and new monsters and hazards have moved in to replace the original guardians, so it's now practically a new dungeon. The artifact, now gone, does leave clues in the main chamber about its powers.

Once they get out and reach a nearby village, they can start to clue in that 20 years have passed. Soon they also discover the really bad news: the evil Rogue has used the powers of the magical artifact for which he betrayed them to depose the old king and steal his throne. Now he's both a king with armies, mages, and spies at his command, and also a deadly high-level character in his own right. The PCs of course want revenge, but they're still low-level and basically alone in the world. The individual adventures of this campaign involve seeking powerful magic treasure and allies to eventually have a shot at taking down the evil king. Of course, as the PCs gain levels and recover treasure, they become more famous, and the king will naturally realize that those he betrayed have somehow returned, and will dispatch his sinister agents to destroy them.

EDIT: Alternate campaign structure, if you want it to be focused on intrigue rather than traditional adventure, is to have the PCs reinvent themselves with the treasure from the first dungeon, and to become courtiers, hiding their true identities from the king. The campaign then becomes an endeavor to manipulate events to ruin the king's life, Count of Monte Cristo-style.