The Fallen Angel (3.5e Quest)
From D&D Wiki
 The fallen Angel
Intended for four level 10-14 adventurers.
Following the discovery of a map with an island labeled "site of the angel's descent" the players sail to the island in question and discover that an angel had descended from Celestia here for an unknown reason. On their arrival, though, the keep is under attack and things are not quite so straightforward as they wished.
- Prep Time 2+ hrs
- Play Time 3+ hrs
 Author's Preface
This quest was run in the Age of Titans (DnD Campaign Setting) over the course of several months and is still continuing. The campaign was based on seafaring, and after the characters successfully took out a pirate ship, they discovered hidden in its captain's quarters a map of a nearby archipelago with one small island labeled "site of the angel's descent." That should be enough to pique any good players' curiosities, but this group had two characters who were brothers both with celestial bloodlines who were interested in finding their angelic forefather. This part is not necessary. What is necessary, unless of course you can think of a way around it, is for at least one character to be a paladin or cleric who is a member of a good church. When I ran it, the church in question was called "The Temple of Light." This article ends where our campaign left off. During the second part both players chose "good" over "light" and then upon discovering that they had chosen incorrectly set off on a quest towards the Temple of Light's primary temple to discover the truth about their ancestry. Naturally at that point there are two ways to go and you the GM can proceed from there however you see fit, and of course the quest itself may be modified however the GM decides.
 Quest Summary
Following the discovery of a map with an island labeled "site of the angel's descent" the players sail to the island in question and discover that an angel had descended from Celestia here for an unknown reason. The keep built over the site has since been taken over by hobgoblins. Within the keep, the adventurers discover a letter from an unknown scholar torn to pieces. Assembling it reveals that the scholar had discovered that the angel in question was a rogue angel who was cast out of Celestia and subsequently turned to evil and formed a church which purports to be good but actually has evil intentions. After being called back by their temple, the cleric or paladin in the party discovers that they may be closer to discovering the consequences of this story than they thought.
 Part 1: The Burning Keep
 Arrival at the island
After arriving at the island marked on the map, the adventurers meet a group of pilgrims who have come to see the site of the angel's arrival on the material plane. The pilgrims are members of a church (in the Age of Titans (DnD Campaign Setting) this is the Church of Kathol) which has built the story of an angel arriving here, doing good works, and subsequently departing into their canon. If the players are able to greet and communicate with the pilgrims they will readily share the story and accompany them to the keep.
As the adventurers approach the keep they may hear a great fire or see that the sky is oddly lit in the distance. Prior to reaching the keep, however, a group of hobgoblins ambush them. If any of the hobgoblins is killed, the rest will flee towards the keep and blow signal whistles they had around their necks. As soon as the players are able to see the keep, read the following:
You see ahead a cliff with what appears to be a natural bridge leading towards a smaller island across a short expanse of sea. Upon it appears to be a single story stone structure occupying the entirety of the smaller island with a few slit-like thin windows along the side facing you. The strangest thing about this structure, however, is the roof, which appears to be completely covered in flames, although the keep does not seem to be damaged by it. At the end of the natural bridge is a single portcullis into the structure which you see quickly close.
The portcullis closes irregardless of whether the ambush team makes it inside or not. If closed out, the remaining hobgoblins will turn and fight to the death.
 The Burning Keep
If any of the pilgrims are still alive, they will lament the takeover of the holy place by hobgoblins and ask you to do something about it if at all possible. However, getting inside is no small feat. If anyone gets more than halfway across the bridge, guards will begin firing arrows out of the windows. Regardless, the windows are too small to fit through without magical means. The roof, as mentioned before, is ever-burning, and there are no more doors or even windows on any of the other three sides, even if the characters are able to access those sides by flying or spiderclimbing. About twenty feet below the structure on the side facing the ocean is a chute where waste exits the keep. This hole is large enough for a small creature to crawl through, although doing so would be extremely unpleasant. Doing so will lead them to one of the basement levels where waste falls from above into a heap and is periodically shoveled out the chute by goblin servants. If the characters make it through the first portcullis they will find themselves in a room with another closed portcullis on their left and right and a grate below. Immediately after entering, guards will light a large fire in the room below which will rise into the entrance and start burning the adventurers after two rounds.
Even if they need a little help, the adventurers should be able to find a way inside and successfully overthrow the hobgoblins and other monsters within.
The inside of the keep should be constructed using guidelines found in the Stronghold Builder's Guide, although it should go several levels into the ground, rather than have any towers or structures rising into the air. At the bottom should be an unholy shrine. Scattered throughout the keep are a series of pieces of a ripped up letter which can be found by a successful search check near where they are located. This can be accomplished by actually writing out the letter, artificially aging it by soaking it in tea and/or repeatedly crumpling and smoothing it, and tearing it into pieces and handing the players the pieces one at a time, out of order, as their characters find them. The letter should read as follows:
To whomever may find this, They'll find me soon and I'm afraid my life is at its end. What I have discovered must be passed on, but if they find this letter they will destroy it, so I must sadly tear it to pieces and scatter it to the wind and pray that the gods let it be found and reassembled by somebody who can pass it on to the right ears. The fact that evil creatures are interested in this keep is no accident. The angel which arrived here was not on a mission of peace, but was cast out of Celestia. He has turned to evil and has established a church here in mockery of the forces of good which exiled him. His church is believed to be good, even by its initiates and acolytes, but its true purpose is evil. The church is called (INSERT NAME) please find it an destroy it before it is too late!
The piece which gives the name of the church should be omitted, as should one or two other pieces for added effect, but the gist should be decipherable.
 Part 2: The Critical Choice
 The Test
After raiding the keep and restoring it either to the pilgrims or claiming it themselves, the cleric or paladin character(s) should receive notification, by magic or otherwise, that their deeds have spread back to their church and they are therefore eligible to return and be inducted into the next rank within the temple's hierarchy.
The church in question should be good, but also dedicated to something related. For example, the church could be a dualist temple (see Expanded Religions (3.5e Variant Rule)) called the "Temple of Light" which is a good temple that believes in light. Similarly, if it were a temple to Pelor, it would be a good temple that in some sense worships the Sun.
Upon arrival at the temple, the adventurers may rest before one last test, the details of which the temple functionaries won't reveal. The players who are members of the temple will be taken one by one to a door. A high ranking cleric will instruct them that they must enter the room where they will be presented with a choice between two doors. They are to choose the door they believe is more auspicious.
When the character enters, they will be presented with two doors. One will be labeled "The Good" and the other will be labeled with the religion's alternative item of worship. In the case of the Temple of Light it was labeled "The Light." The character will have as much time as necessary to decide which door to enter. If they attempt to use any magical means to see what's on the other side, it will reveal that both doors lead to similar rooms with similar another high level clerics behind it.
 The Good
If the character chooses the door labeled "The Good" they will enter a room with a high level cleric behind it. The cleric will say the following:
"My child, you have chosen correctly. The Good is always most important, regardless of other concerns. You will receive your next rank and then will be free to continue your travels. At this point whether you are called upon again is up to the elders of our Temple. It may or may not ever happen, but no matter what, you should be proud of your strength and resolve."
Questioning the cleric will reveal no significant new information. Later, during the festivities, one of the other characters in the party should overhear one of the priests say to another, "So he chose incorrectly... that is unfortunate" or something similar. If they question others who have taken the test, it will reveal that all of them claim to have chosen "The Good" and they therefore assume that the other choice was the incorrect one. More thorough investigation (possibly charming clerics) will reveal that this Temple was started centuries ago by an angel who came from Celestia to the material plane, though no one will know much more than that, and will refer you to the main Temple which is somewhere very far away.
 The Light
If the character chooses the door labeled with the church's alternative they will enter a room with a high level cleric behind it. If the Temple of Light is used, the cleric will say the following, otherwise edit this for whatever relevant religion is used:
"My child, you have chosen correctly. The Good is dependent on the circumstances and undefinable. The Light is constant and clear. If given a choice between what serves good and what serves Light, we must always choose Light. Now listen carefully, for this is important: Had you chosen The Good, the priest behind that door would have told you that you had chosen correctly. You then would have received your next rank and would have been sent on your way, never to be called upon by the Church again. If anyone other than someone of higher rank than yourself ever asks you, you are to tell them that you did in fact choose The Good. This is true even if the person is a close friend or family member. Unlike those who actually do choose the Good, however, you will be called upon again in due time. Now go on to the festivities, and congratulations."
The character may then do with that information what they will. If they ask this cleric or any other present, they may discover that the Church they are a part of was in fact started by an angel who came from Celestia to the material plane centuries ago, but those present will not know any more details about this event.
As mentioned in the preface, this is as far as the quest got. If the characters chose The Good and asked a lot of questions, the Church may send an assassin after them. If they chose The Light, the Church may start calling upon them for increasingly morally dubious activities. Regardless, it's up to the DM where to go from there.