Eberron is a place of dark adventure and intrigue; many things are not what they seem and even when a mystery is solved, questions still remain. In a world where changelings can take the face of anyone, mistaken identity is commonplace and some use that to their advantage. This adventure seed blossoms over the course of several days. The PCs may get involved at the start or ignore it as background material (perhaps reading about it in the local daily chronicles) until circumstances press them to act.
Step 1: A Murder Witnessed
While the PCs are in a city, witnesses see a well-known person (an adventurer, aristocrat, politician, or perhaps even a well-known criminal boss) stab someone in an alley, burn the body with oil, and run away before he can be captured. The next morning when he is found and arrested, he denies involvement in the crime but cannot account for his whereabouts at the time it occurred (perhaps something as simple as drunkenness or as complex as being on another plane or under a spell). He insists that someone is framing him. While the authorities are investigating the murder and arranging for magical verification of the accused's story, another strange death happens.
Step 2: A Second Murder
In a tavern frequented by wealthy individuals, a man wearing a hooded cloak enters and begins accosting the patrons. A scuffle breaks out and the man slips and hits his head on the bar, dying instantly. The other guests are startled when they pull back the hood and recognize the face of the person accused of the alley murder (as gossip-runners have already circulated the news of the man's arrest). The accused's advocate uses the discovery of this look-alike to convince the judge that the man is being framed, and the judge releases the accused with the order to remain in the city while the investigation takes place.
Skeptics spread the rumor that the dead man in the bar was actually a poor changeling paid to impersonate the accused in order to get the man out of jail. This causes protests from the changelings in the city, who rightly point out that when their kin die they lose whatever face they were assuming, which means the dead man from the bar cannot be a changeling. Tensions remain high and the already-mistrusted changelings continue to suffer abuse despite the truth of their claim (a counter-rumor quickly makes its way through the city, suggesting that some changelings may be able to maintain a face even in death, and therefore the complaints of the changelings are just to cover up the proof of this "secret" ability).
Step 3: The First Victim
The day after the death of the man in the bar, a mortician examining the burned body of the first victim notes with surprise that the corpse is that of a changeling--presumably it was disguised at the time of death, and the fire kept its features from fully reverting to normal, delaying the identification of his race. This is a lightning rod for the changelings, who are incensed that one of their own has been killed and they have been blamed for trying to free the man responsible. The accused murderer goes into hiding because of threats against his home and person. In an attempt to keep the peace, city officials promise a full investigation into the changeling's death, though the burned corpse means it will take longer to identify.
Step 4: A Third Death
Two days after the death of the changeling in the bar, another person turns up dead in the city--this time, the man accused of the alley-stabbing. His body is pierced with two crossbow bolts, one in the back of his thigh and one in the middle of his back. Both bolts are poisoned, though the bolt that pierced his heart would have done the job without any poison. Once again the changelings fall under suspicion, as it looks like a retaliatory attack. Others believe it was the action of vigilantes who feared the victim's status would allow him to escape punishment for the crime he (allegedly) committed. A minority believe it was assassins or old enemies taking advantage of a situation where the victim had to avoid public places (making killing him easier with no witnesses).
There are several ways to get the PCs involved in the plot.
PCs Are Witnesses (Step 1, Step 2): The PCs witness the original crime in the alley. They may try to apprehend the murderer (whether or not they recognize him), but he should escape somehow, either by clever use of terrain, mixing with a crowd, timely arrival of a carriage, or magic such as invisibility or teleportation. The local authorities ask the PCs to remain in the city until the investigation is concluded (this allows for some downtime after a big adventure, giving the PCs time to train, create magic items, and so on). If the PCs leave after being asked to stay, they also become suspects in the crime. Similarly, the PCs may witness the bar fight that results in the cloaked man's death. If one of the PCs is a changeling, they may later encounter angry mob wanting to deal with "the changeling responsible."
PCs Know the Accused (Step 1): The accused is a friend or mentor of one of the PCs, a long-standing rival (friendly or otherwise), or someone prominent in an organization to which the PCs belong (such as a church). This biases the PCs in the eyes of the law as they cannot be expected to remain totally impartial. If the PCs join the investigation or act on their own they will need to be very careful so their integrity remains uncompromised.
PCs Are the Accused (Step 1): The easiest option for this adventure hook is to have the accused PC elsewhere in the city at the time of the murder--while he knows he is innocent, he has to find a way to prove it. However, in the spirit of intrigue, it is more interesting to have the PC not know if he committed the crime; perhaps he was under a spell, insane, dead, sleepwalking, or amnesiac, any of which leave doubt about the PC's innocence.
PCs Know the Victim (Step 1): This connection may not be immediately clear to the PCs. However, if the murder occurs on the night of a clandestine meeting between the PCs and some informant, and that informant fails to show up and thereafter is missing, the PCs should be able to put two and two together. If the victim is their contact, who was trying to silence him and why? This plot element works even if the PCs' contact is not a changeling (for example, the PCs may not know that their "dwarf" contact is actually a changeling).
PCs Know a Changeling or are Changelings (Step 2, Step 3): Any changeling PC or PC with close ties to a known changeling is going to suffer from the backlash when changelings fall under suspicion for these crimes. Likewise, NPC changelings may pressure the PCs to protect them from non-changeling hostility, and especially radical changeling allies may push a changeling PC to abandon his non-shapeshifting friends, as "they all think we're murderers."
PCs are Swept Up in a Riot (Step 2, Step 3): Whether the rioters are changelings angry at being called murderers or (more likely) non-changelings looking for some vigilante justice against those no-good changelings, the PCs can play a pivotal role in quelling the mob; bardic music and spells such as hypnotic pattern are very useful for pacifying large numbers of civilian hostiles. If the mob has already selected its target, the PCs may have to intervene to save someone from a beating or even worse.
PCs Find the Accused's Body (Step 4): This may be something as simple as the PCs finding the body behind a favorite restaurant, as adventurer-mundane as finding the body in a cell in a (supposedly) unrelated dungeon adventure), or as unexpected as one of them waking in her room in the inn and finding the body on the floor with no explanation as to how it got there (which of course puts her under suspicion).
These options only explain how these things happened. The nature of your campaign, the abilities of the PCs, and the enemies they have encountered should determine who is responsible for these events.
The Accused is a Changeling: He and a cohort kidnapped the famous person and assumed his identity, but his partner in crime turned out to be a liability and the accused had to kill him to protect his own interest in the caper. The burned body is of the accused's partner. But who is the dead man in the bar? And the man killed with a crossbow? Alternately, there was no kidnapping. The murder in the alley was staged using an impersonated identity to ruin that person's reputation. But who was the murdered changeling, and was he complicit in this staged crime due to some severe debt? What about the man in the bar and the one killed by crossbow?
The Accused is Not a Changeling: The famous person is really the one who killed the changeling in the alley. Did he do it deliberately? Or was he under some sort of mental control or blackmail? Was he supposed to be caught? Is the man killed by a crossbow the original or another ruse?
Illusions: While there are no illusion spells in the Player's Handbook that let you assume the physical appearance of another specific person (disguise self helps you make disguises), there may be a wizard who has developed such a spell. Is the murderer in the alley just an assumed disguise? Is the man in the bar an attempt at an alibi, and was their death an accident? Is the third body the real deal or another unfortunately-disguised victim?
Polymorph: Similar to the illusion explanation, someone involved is using form-changing magic. Polymorph reverts at the time of death, so unless someone is using a variant of the spell that doesn't revert, the accused is a polymorph-disguise. Even stranger, someone may be using a permanent or instantaneous spell on a corpse to make it look like the accused is dead. Who would go to such lengths, and which of the two non-changeling bodies is the real person's body?
Simulacra and Clones: Though it has limited combat uses, the simulacrum spell is excellent for sowing chaos and mistaken identity. Any live person involved may be a simulacrum--the accused, the mortician, the city official in charge of investigating the murder. Clone is problematic (the original needs to die first) but still useful; any dead body (such as the one killed by crossbow) may be an inert clone. There is also the possibility that someone has found a way to revive these inert clones and control them like puppets (whether through mental domination, infusion with an undead spirit, or possession), which means the accused and the man in the bar may be clones as well.
About the Author
Sean K. Reynolds lives in Las Vegas and works as a world developer for Upper Deck as well as running his own small press d20 company. His D&D credits include the Monster Manual, the Forgotten Realms Campaign Setting, and Mysteries of the Moonsea. You can find more game material at Sean's website.