As a Storyteller, I have a couple of default stories I like to run. One is Alien Hunger--my absolute favorite adventure published for Vampire; it's particularly solid for new players. But, I also have a few that I've developed over the years that are my “go to” stories, which I like to run for a variety of players, new and old. “Bug Hunt” is the main one of these.
It is, in effect, a classic Vampire vs. Vampire conflict, with an added element of the Beast vs. Humanity. The basic idea was stolen from another player in a game I played in years and years ago. He wasn't a huge fan of Vampire, and wanted to do something different and a tad wacky with his character. The basic concept was Kafka’s Metamorphosis. He played a Nosferatu who had gradually lost all concept of Humanity, and viewed himself as nothing more than vermin.
The character was certainly fun, particularly since my character and another had “adopted” him and were trying to help him get back to being “normal.” For the story, I make his character into the titular “Bug.” There’s a neonate Nosferatu on the loose, one who has lost all semblance of Humanity and has become a beast. The players, quite simply, need to hunt him down and put an end to his deprivations.
Sometimes i give him more motivation (such as protecting his family, with characters often stolen directly from Metamorphosis), while other times he is more of a monster, or a force. It allows for a fairly clear cut story--the players, after all, know from the get go what they need to do. But for such a simple story, it can rapidly become more. Such as exploring the nature of the Beast, and why you would want to nurture your Humanity. As a vampiric foe, it also introduces the difficulty and complications inherent in trying to struggle with one, particularly when your foe has a good amount of feral cunning. I tend to look at the coterie I have for this particular Chronicle, and try to emphasize those elements that I feel would be most interesting for them to struggle against.
As far as the story itself, I tend to run it as more of a “scenario” than a “plot.” The story almost almost always begins at a location at least one the characters cares about--such as their club, or something similar. Mr. Kafka has slain a mortal and stuffed the body in the ceiling, and the players need to find a way to keep this hidden from the mortals currently filling the venue, as well as find out who did this, and why. My prep basically consists of figuring out what Kafka is up to, and where he hangs his hat. After that, I let the players loose in trying to hunt this bug down.
Normally, this has been my “opening scenario” to a Chronicle, though I imagine it might work even better in the middle of a game. Using it as the first adventure works to give them a clean, neat story, with a foe on their “level.” However, it also cuts down on the ability to make him a spoiler. If the coterie were currently feuding with another band of Kindred, or already on the Prince’s shit-list for some previous wrong, having him show up and cause havoc might have more of an impact.
Of course, I like using variations on this at other points. The “bug” doesn't have to be Kafka, after all. A hunter, Lupine, or Sabbat--really, any solo foe the players need to hunt down and eliminate could be used for this, and I've used pretty much every enemy I can think of. Subtle politicking and manipulations are fun, but sometimes putting the players on a hunt across the city, seeking the destruction of an out and out “bad guy” can be a wonderful change of pace.