A vicious murder happens in a town that the party happens to pop in at. Under heavy suspicion as they are strangers, the party is forced to discover the perpetrator or have their reputations blackened, especially as more and more murders occur in the town, and mysteriously stop and restart when the party leaves to go kill off that evil necromancer who kidnapped the princess.
The only problem is that a demon, possessing one of the party, is the perpetrator. And the demon makes no signs that its living in the PC's head.
In fact, for all the party knows (except for the possessed person's), their companion is an evil murderer.
Do they try and execute their friend as he's a vicious murderer, and no evidence points to demonic posession? Or do they flee town with him, trusting him, and have their reputations destroyed?
After the PCs defeat (or force the rapid retreat of) a villanous necromancer/demon summoner, they discover a book. This book outlines how to summon a demon whose power increases according to the size of the summoning circle used to summon it. And after the PCs examine a map of the country, they find that the layout of the cities and roads match up with the required summoning circle. In fact, the final road that would complete the circle is currently in construction.
With anyone who can find out about the circle and the ritual to summon the demon able to somehow make the final road/line, and destruction of the cities and roads currently in existence out of the question (unless this is an evil campaign- that removes the moral quandary), how are the PCs going to solve this problem?
The PCs are walking along the road, when suddenly a bunch of bandits attacks. The player's dismiss it has just a random encounter, when they find an ornate ring on the leader, obviously out of place with the seemingly poor bandits, who could only afford cheap leather and weapons. This ring has a symbol on it, which, if researched, sets the PCs on a quest. And from then on, the players don't look at random encounters the same way...
The secret for immortality has been discovered by an eccentric wizard/mad scientist. Its found you need to reapply once a month. As people stop dying, and the birth rate increases exponentially, people are forced into homelessness, because of the need for food reamins the same, and food is not being produced fast enough to feed the undying population. The PCs have to find the creator and kill him, and destroy production, to save the world from undying, unending torture from hungryness.
The journey had been a long one and now they had entered the mountains. After an entire day spent on paths cut into the mountainside and through moss covered coniferous woods, they encounter a desperate young mountain tribal. He is searching for his beloved wife and his elder brother, both of whom he got separated from after an unsuccessful attempt to kill a cave bear. The last thing he saw was the cave bear in full pursuit of his wife. He could not help her as he had been knocked to the ground by the raging beast, and was struggling to regain full consciousness. The tribal will be clearly nervous and urges them to look for his wife during their travels. He will stay in his village a couple of miles to the north and pleads for assistance should they recover his wife, whether she be dead or alive.
On the next day of travel, they will journey upon a dim track in the forest and while they are preparing to ascend another path cut into the mountainside, they hear moans of lust from somewhere nearby. Upon closer inspection they will spy a young tribal woman in the heat of the act with an elder tribal male. They are consummating their forbidden love on the cold mountain moss, and beside them lay the skinned and slaughtered carcass of a huge bear.