As chance happens, the players find out that the next appearance is due and set out to watch the spectacle. The castle appears, the players enter the castle and the lord begs them to get the dragon to attack the castle, so he can fulfill his quest and find peace. He promises them the castle and its treasures if they succeed in their quest.
So the players set out, find the dragon's lair after some difficulties, and stand before the skeleton of an ancient red dragon and the burnt plate mail of the knight that killed him. Hmmm...you need the dragon alive to let him get killed again by the lord and his knights. "Ok, so let's resurrect him!" (Considering that this was a really evil dragon that scorched several cities, ate dozens of virgins, and so on, this might not be easy choice for the players, Wha ha ha!:) They do it (scared out of their socks, hopefully) and have to persuade the dragon 1) not to eat them, 2) to let himself get killed by the lord, 3) eat them after he scorched the castle (hoping the knights succeed killing the dragon...they're only phantoms after all...), 4) generally let them live.
In short, they have to think about what they do with the dragon after they fulfill their quest.
But the dragon suffers from a permanent alignment change and can now be considered chaotic good, with a slightly pyromania or sadistic (err...He's got this hungry look in his eyes again, guys!) touch maybe... It's hard to get used to being good if your only experience on normal social interaction with other beings consists of setting them afire (knights) or eating them (virgins). Maybe the players become just good friends with him. Note that this plot itself involves no fighting, if the players do it right. It would be better for them if they did, anyway.
A silent night in town
The players arrive in their favorite tavern, maybe returning from
some awesome adventuring, and they are looking for some fun, which
consists of relaxing and having a drink with their buddies there. The
overall atmosphere in the tavern is relaxed and joyful, with some
people playing darts and an old grandpa
telling stories to his audience. If the players decide to listen, he
will just happen to tell the legend of Lord Shibban and the Dragon
(See Lord Shibban and the Dragon). If they
decide not to listen, he tells the story and after finishing it will
take a seat close to the players, mumbling things like "the young
don't listen to the stories of old anymore...where will it end when
the virtues of honor are not spread any more..." and "ahh...they
don't believe me...Ignorant little rats!" while ordering some spirit.
If the players talk to him, asking about his anger, he will eventually tell them the legend. If they don't ("Ignorant little rats!"), well, they just missed a chance for glory, wealth, attractive women/men and instant death, if you don't come up with another way to let them swallow the hook.
The Storyteller:
His name is Grundar, and he is an old guy from around here, who has
spent his time in the service of a knight, thus hearing many legends
and lore. He now tells his stories to whoever wants to listen, hoping
to earn a drink or meal. He firmly believes that every legend has
truth in it.
Depending where your players are located, there are several
possibilities to gather more info:
Lord Shibban had thus violated his oath, putting him and the knights into an eternal state of restlessness after their deaths. For they did not find peace, they had to wander the world until they fulfill quest, forever bound to the castle, till they either killed the dragon or died at the attempt. Still the castle appears somewhere in the mountains, and it will do so until Ember the dragon sweeps past again.
Arriving at the castle
The castle is nothing more than some crumbling ruins, situated on the
top of an idyllic wooded hill. It was abandoned due to the phantoms
that roamed it several hundred years ago, and not much is left of it.
(Note that the castle is always here, but the phantoms exist only
when the constellation is right, contradictory to what the legend
says.)
The Phantoms
The phantoms of Lord Shibban and his knights and men-at-arms appear
as dark shades of their former selves, still recognizable with their
armor, clothes and weapons, but can't interact with their
surroundings. The only method of communication is telepathically
through pictures. They perceive their surroundings as a mental image
of the life-forces that surround them and don't know about the
castles state of disrepair. For them it exists as they remember it,
which can be quite weird when they open and walk through doors that
only exist for them, and avoid obstacles that aren't there, following
hallways and avoiding walls where there are none.
When the PC's arrive, they will be greeted (by gesture only, of course) by phantoms that hover in the air where once the castle wall stood. If they ride into the castle before the guards 'open the door', this will give them some suspecting looks.
They will then be lead into the former throne room of Lord Shibban (have fun on the way!), who already sits on his throne as he has done for centuries. He will then telepathically show them pictures of his story, which are essentially the same as stated in the legend, and then the dragon that sweeps over the castle again and again, always attacked by Lord Shibban and his followers. The final pictures then shows a peaceful burial ceremony for the fallen soldiers and the corpse of the red dragon, with the player characters as bystanders.
For the PC's, the next step should be obvious: locate the dragon and get him to the castle, which involves further information gathering first. It is assumed that the PC's will do it, for the castle and its treasures should be a worthwhile prize. If they object, I'm afraid you have to come up with something yourself. Maybe if you have a knight/paladin or cleric in the party, these characters can be motivated by reminding them of their faith/oath or whatever, that it would be a good deed to lay these restless spirits to their peace. And the dragon's treasure is there to be found, too... (At least this is what the players might think.)
In pursuit of Ember
Some questions the PC's have to answer:
What happened to the dragon:
The dragon travelled east wards over the sea, found a new cave, a
country to devastate as well as a knightly order with some potent
members. One of these, Sir Reginald, set out to find the dragon and
kill him before he was able to wreak havoc. He succeeded, but never
returned from his quest, as the dragon burnt him before he died. So
no one knows what happened to the dragon and Sir Reginald, nor about
their whereabouts. And all this happened some centuries ago.
What the players can find out is that the dragon was last seen flying east wards, and the year when this happened (again in the library), but that should be all for now.
They will then probably have to travel east to find more evidence of the dragon. I suggest this involves a ship journey, as it will make things a little more difficult for them if they intend to first bring the dragon skeleton to the castle and then resurrect him. Throw in some encounters or subplots as you like.
Upon their arrival, they have to check out if the dragon was sighted here, and indeed, old reports point to the center of the country, as well as giving a clue about the knight that set out to destroy the dragon. A visit to the knights order will reveal that Sir Reginald set out, but never returned, likewise the dragon was not sighted anymore. But they will be shown the general area where the dragon's lair was suspected (the exact location is again up to you, as are so many other things).
Arriving in the area, one thing that could lead to the lair can be the name of a local geographic feature, maybe a mountain is called Dragon Mountain or Knights Demise. The players will then have to search this feature thoroughly and eventually stumble across an old cave, the entrance nearly overgrown with bushes. Making their way through the tunnel system (make this as big as you like, if your players enjoy some good dungeon crawl), which is way too small for a full grown dragon, they enter a huge cave. The first thing they notice is a scorched, very old plate mail, then a huge white draconic skeleton. Obviously, the ceiling/exit of the cave collapsed during the battle, capturing Ember who was already mortally wounded. If you are a nice DM, you may have noticed that pile of gold and gems beneath the skeleton. But as the players should come pretty easy to the conclusion that they have to bring the dragon back to life if they want to succeed, this might not be that nice...who dares to steal from a dragon, after all?
The players are facing several problems now: most important the decision whether to resurrect the dragon or not (in my campaign, this was MUCH FUN to watch), drop in any nasty remarks as you like ("You REALLY want to do it? *grin* Are you absolutely sure? *chuckle* Don't blame me afterwards..."). Someone who has the might to bring a dragon back to life has to be found, and maybe the problem of transport has to be solved, if they decide to resurrect Ember at the castle, not here. Maybe the players come up with some other idea, and if it sounds reasonable, let it work, as long as they don't avoid that critical moment when the dragon actually turns alive.
Who has the power to resurrect the dragon is up to you, I suppose. Several possibilities:
Possibility one would be the safest of all in terms of plot advancement, but is somehow too simple in my opinion, the second one is ok, but not very imaginative. The third is good in my opinion, as it offers the most possibilities in terms of role playing, but also the most problems if you don't handle it carefully. But imagine the players proving to everyone that this dracolich friend of theirs is a really nice guy! Finding a potent Necromancer can also be quite messy, cause who knows what his aims are?
I regret not being able to offer you a solution for this part of the plot, but it depends heavily on your campaign and your PC's resources, and with the suggestions made above, you should be able to wing it. Therefore, I suppose they manage to somehow get back to the castle with a living Ember.
Ember, the dragon
The stats are up to you, but I suggest that he is quite powerful
(adult to old in AD&D; terms). He was once a really evil being,
destructive, enjoyed watching people burn and so on...quite the
standard red dragon. What is special about him after the
resurrection/animation or whatever is that he is not the same
anymore...the long time dead or a small error in the spell has caused
an alignment change.
Of course he still has problems getting used to being good, as old habits are difficult to change, but small "mistakes" should be seldom and more fun than a nuisance to the players, who have to play "babysitters" to prevent any accidents. People's reaction are rather strange, anyway.
Back at the castle
After the resurrection, Ember will slowly lift one eye, then the
other one, take some time to reorient himself...and then focus on the
PC's, demanding to know what happened etc. The PC's have to persuade
him to attack the castle, which should not be THAT much of a problem,
considering Ember's alignment change. Of course, the players have no
possibility of knowing this, so let them sweat!
After some discussion, he will agree and fly towards the castle, where the phantoms are hurrying to the walls and towers, the alarm bells start ringing etc. Then Lord Shibban, followed by his knights, will ride forth and attack the dragon without being able to hurt him, but perishing and disappearing with the dragon's deadly blows (that sweep through them without noticeable effect other than the phantoms dissipate and find their peace.
(If your players haven't noticed the dragons alignment change and thought that Lord Shibban would kill the dragon, thus saving their lives, this is serious fun!)