Gonna try to keep this in a modern horror setting without going all post-apocalyptic.
Content Warning: Zombies, gore, body horror.
Plot Idea 1: The group is contacted by an antique dealer in their area who has come across a very rare and powerful book- a copy of The Necronomicon Ex Mortis. It’s not the original, obviously. However, he is curious whether or not the certain members of the group would be interested and how much someone might pay for such a tome if it were a real, legitimate copy. He mentions he has contacted a local professor of Egyptology and another antique dealer, Mr Stephen Vendredi.
When the PC’s arrive, the antique store is trashed and their contact is deceased in the back room. Some investigation reveals he was stabbed by a silver athame and the handwritten receipt indicates he did indeed purchase the book. Later that night, the dead antique dealer rises as one of the walking dead and wanders out of the coroner’s office.
It eventually turns out the Professor of Egyptology, Dr Leonard Parnell learned of the book becoming available but did not have the funds to purchase it legitimately. He firmly believed it could lead to immortality if read and cast properly. Unfortunately, one murder lead to another and then more to try to cover for his malevolent deeds. Exposure to the book and its spells drove the doctor to madness.
Plot Idea 2: An overzealous teenager manages to get himself possessed by a demon in the name of science. He invents a mind control device that turns people who hear its sound into cannibals who feel no pain or remorse and will continue craving human flesh until destroyed. Luckily, he starts off small, first with one victim, then a family, and finally an auditorium full of people attending a city council meeting. All the group has to do is destroy the device without being infected by it using special ear protection.
The other plus is those attacked do not return as zombies. The sound is not replicable by human vocal cords at the present time. Another ulterior motive of the Zombie Lord is to create thousands of hosts for his demon brethren to inhabit. The Investigators would do well to contain or destroy the threat themselves before the SCP Foundation or some other clandestine operation shows up to “help.”
(SCP Note:) The 05 Council has deemed the “Zombie Lord” to be a Keter Class Info Hazard. The device must be taken into custody along with the person who built it. If that signal were broadcast over the internet or mainstream media even for a few seconds, it could lead to a zombie apocalypse. Special ear plugs are to be issued to all personnel before they come into contact with the device. The device is to be taken to a secure site immediately upon retrieval. Some believe this may be a variant of SCP 1237. Anyone on the scene of an outbreak must be given heavy amnestics or destroyed immediately.
Plot Idea 3: Scientists at a well known tech company are experimenting with neural linked implants that could increase various skill functions in humans. In order to speed up the “rewiring process” nanowires deployed by bloodborne probes are employed. The experiments’ subjects are all paid volunteers and the experiments are being conducted in a black site somewhere near our heroes.
Unfortunately, one of the test subjects died. Rather than do the responsible thing, facility cleaning crew tossed the body in a dumpster. Various varmints, raccoons, possums, and rats fed on the body. They became infected with what the research team thought were inert bloodborne probes. They couldn’t have been more wrong.
Now the group is faced with a handful of possible zombie animals and one zombie human. It turns out the probes did their job a little too well, but slower than expected. The probes need sustenance, preferably something heavy with neural tissue such as a brain, for example. Now the Investigators must put a stop to the zombies, find the facility, and shut the whole operation down before more people are injured.
The probes are only spread by feeding on an infected host. It may be possible to short out the probes with a radio signal that short circuits them and/or tells them to become inert. The nanowires can never be removed, but the host can be programmed to shut down.
Jeff's Game Box 