An adventuress, Semma, has returned to her home village, but something has gone badly wrong: it's the furtive glances, the conversations that stop when she approaches, the childhood friends who now have no time for her. She returns to the town or city and enlists your party to help her find out what's going on.
The party must find out what is wrong: something (perhaps a Cthulhoid monster, perhaps a gang of vampires, perhaps just a bunch of bandits) is extorting obedience from the villagers by threatening their loved ones with at least death. Once the source is discovered, Semma and the party and a few brave yeomen (and women) must deal with the threat by finding its base and defeating it, and then deal with the remnant corrupted villagers who willingly served the Evil Force. These may prove to be the most difficult foe...
A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for 'study' by the Guild. The party's presence will be 'requested' for this expedition.
Ursula is a were-bear; she and Stewart, the bailiff of a rural feudal estate, are lovers, sharing all their secrets as lovers often do. Recently something has been taking livestock. *He* must deal with suspicions that a bear is involved (one has been seen nearby...): *she* must defend herself if it is revealed (perhaps by a jealous suitor, perhaps accidentally) that she is a lycanthrope. The adventurers might be called in to track the hungry beast(s) and discover her secret, but be able to reveal that the culprits are a small pack of wolves that has moved in to the area. The adventurers might earn the gratitude of both Ursula and Stewart, depending on what they reveal, and to whom.
Just off the road a man lies dead, pierced through the heart from behind by an expertly thrown and ornate dagger which remains in the body. A long strip of cloth torn from the man's shirt has been tied around his neck; on the tag end an unknown hand has written a cryptic inscription: "For Djaygo."
When you get to the next town, everyone is talking about a mercenary woman found slain in exactly the same fashion in her room at the inn where she was staying.
With a huge number of sacrificial victims, another realm long ago secretly bound a Prince of the land spirits, Iorstonn by name, thus ensuring the fertility, and improving the magical defences, of their realm. But binding that Prince to one spot has disrupted the weather and magical patterns (ley lines?) over half the continent. Things have become bad enough that a coalition has been formed to rectify the situation, once divinations have established the cause.
Your party is one of the teams assembled to do the rectification: find the binding object and steal it ("so that we can destroy it here in our realm, of course"...*) or destroy it over there. Presumably the Prince will be grateful to his rescuers and angry at the binders, but with a greater spirit like Iorstonn one can never be sure: such beings are "tricksy".
* Of course, the rulers of our realm might want to control Iorstonn for their own ends...
You receive a vision of a rooftop "somewhere close by", where a rare moss grows; in the vision, you know the moss is suitable for greatly enhancing the effects of certain types of potions. Now go and find that rooftop. Don't fall off. (Of course, rooftop runners *will* be taken for miscreants by the local City Watch....)
A shape-shifter of some sort has taken up a post at the War College of an enemy realm, where he secretly picks off only the most promising officer cadets, arranging bizarre accidents that gradually debase the leadership of the hostile army. In the long run, this will improve his nation's chances when the inevitable conflict comes.
As a shape-shifter he can impersonate superiors and peers alike and send the target candidate to the cleverly-prepared site of his (or her?) execution. As long as he is successful, no-one will ever know about the deception--even necromancy will only implicate the one impersonated...
You pass through a woodland with a floor that seems remarkably clean of debris. Suddenly your attention is drawn to a twisted bit of wood by the trail side, a short broken twig with several stubs of branches along its length and most of the bark missing. When you reach it, the twig blurs and turns into a small brown lizard, caught in the middle of its body-twisting run. The little reptile darts away down the trail with impossible speed, no doubt magically enhanced, and is lost to sight in a moment. Now someone knows you are coming...
Some parallel worlds have different time-flows, like the fabled dwelling-places of the elves: those who visit them under the hill for a night return to find that years have passed in this world. Perhaps it is the gate leading between the worlds which causes the alteration. If a gate were 'misaligned', the shift from '| |' to '| \' or '| /' as it were would lead to that difference, much as a light-beam split and bent by a prism ends up taking a longer path. There might even be a mathematical function linking degree of misalignment to alteration of time-rate.
As population increases, animal souls are promoted to human before they are spiritually advanced enough in terms of impulse control, etc.: this shouldn't have happened, but karmic progression is automatic, after all--it's a force of nature. But the 'animalization' of humankind bodes ill for civilization.
No doubt the same goes for elves, dwarves, and so on.
The multiple-worlds theory of cosmology allows room for every religion's Heaven and Hell and other planes to coexist, with the similar planes of all the sapient beings of all the worlds in all the galaxies...How often do the wires get crossed, as it were, leaving your paladin in a Hell for hedonistic lizards, for example.
The court wizards of Angolterre have been working for several generations to protect the dynasty. They see to it that the new monarch's names acronymically refer to a rune of protection. Once completed, the rune will make the dynasty almost invulnerable in battle, wise in counsel, etc. Unfortunately the next name, the only one that starts with the right letter, happens to have belonged to the worst monarch in living memory. Not much chance of getting the current ruler to name his child that, or for the people to put up with it if he did! What's a court wizard to do? The magic requires that the plot be kept secret of course...
By late afternoon, the sky starts to cloud over. The sun shines behind the fluffy clouds, gilding the edges and showing a Jacob's-ladder of rays streaming through the gaps...very pretty. Gradually the clouds shift into a new configuration: you realize with awe-struck, preternatural clarity that the clouds form a map of a coast-line that you know against the blue sky as ocean: surely it's a Sign! Suddenly, the golden beams coalesce into one long ray that strikes across the blue. A star-like gleam flashes under the ray: perhaps it is an island? But the charts show no island there...who would want to hide an island? Who could do it?
Real World: some Indians in the Amazon treat their eyes with a traditional potion applied with palm leaves. Brutally painful, the drug alters vision, giving the jungle's dense green walls greater texture and dimension. You could adapt this to desert or swamps, or other hard to navigate regions.