This adventure hook is designed for a Call of Cthulhu or Realms of Cthulhu setting although it could easily be adjusted for any other setting which involves magic of one type or another.
Edmund Ralfone is a respected police detective. He is also the leader of the Cult of Hollow Earth, a group whose goals include gaining power and immortality for it’s members by way of transformation into Ghouls. As the cult leader, Edmund is entrusted with many artifacts the cult has collected over the years including the Disk of Oberu, a black disk measuring five inches in diameter and almost an inch thick in the center, tapering down to less than a quarter of an inch along the rounded edge of the disk. The disk also has carvings and symbols etched into its surface which are almost impossible to see as the Disk of Oberu reflects little if any light.
The disk came to the Cult of Hollow Earth with a story that it was used by an ancient arcanist to control a creature of night so dark as to be nearly invisible as it flew along the night sky. The arcanist had, so the story goes, used this creature to dispose of his enemies by having it catch them in its grip while they slept, carrying them to incredible heights and dropping them to their death.
Edmund hadn’t thought much of the artifact until his own enemies, both within the Cult and without, became such an issue that he had to find a way to deal with them or risk being eliminated and replaced. Edmund spent several days studying the disk and found that by setting it on the correct side and spinning it counter-clockwise while saying an incantation it could be activated.
Ecstatic, Edmund cleared his evening schedule and performed the acts to summon the Nightgaunt but to no avail. The disk began to glow a faint sickly green but no Nightgaunt came forth. After trying several more times, Edmund eventually went to bed disgusted.
Unfortunately for Edmund he missed two important facts in his research. First, the Nightgaunt only appears when the summoner falls asleep, creating a conduit to the Dreamlands which brings the creature to our world and sends the summoner to the Dreamlands. Second and more importantly, the disk must be hidden from the Nightgaunt. If the Nightgaunt can find the disk then it is no longer bound by the summoner’s will. Even worse, it can use the disk to force the summoner to do its own bidding while he walks in the Dreamlands.
As a result, the summoned Nightgaunt appeared as Edmund fell asleep and quickly grabbed the disk. It immediately left Edmund’s home and flew around the city, killing two victims that night while it forced Edmund to work for it within the Dreamlands.
Now, two days later, a desperate Edmund Ralfone is looking for someone to help him “solve” the strange murders plaguing his city. Four victims in three nights have been killed by apparently being dropped from great heights or by being eviscerated by some strange wild animal. Edmund managed to get himself assigned to the case but doesn’t have much time. He needs to retrieve the Disk of Oberu and take control of the Nightgaunt before his enemies within the Cult of Hollow Earth begin to put together the pieces. He also needs to solve or at least stop the murders before his inability to do so results in having another detective assigned to the case.
Edmund approaches the Investigators (Players) with an offer of a job and a reward if they can help solve his case. He is able to give them access to crime scenes and autopsy reports. He is willing to pay a pretty hefty price if the Investigators are able to retrieve the disk.
The ensuing adventure could go in many different directions after the Investigators are brought in to help. If they are able to quickly retrieve the disk they may be having a drink the next night to celebrate when they hear on the local news that another murder has occurred. At that point they will probably realize that Edmund was more than he claimed and lead to their uncovering the Cult of Hollow Earth. If they are slow to find the disk and stop the Nightgaunt things could get even more complicated. Another detective could be put on the case and may or may not approve of the Investigators’ involvement. Edmund’s enemies within the cult could realize what is going on and start looking for the disk themselves, even going so far as to tail the Investigators and possibly attack them once the disk is found.
There are many other possibilities that could occur as well. Even if things go well and they manage to stop Edmund and the Nightgaunt, the Investigators are then left holding the Disk of Oberu. It could be very tempting to use such a powerful artifact at some point in the future which could have any number of strange side-effects. The disk could also contain other properties besides the ability to summon the Nightgaunt. And of course if anyone else knows about the artifact, it is a safe bet that someone will eventually come looking to take it for themselves.