Alright, here's a basic plot that I've come up with:
The Withered Rose
-It's no secret in the Inner Sea that the Goddess Shelyn and her brother, the warped god Zon-Kuthon, have been at an uneasy truce for years. Once twin deities with power over Love, Beauty, and Art, the two fell apart when Bal Thoa forsook his domains and left this plane, hoping to find something that would make him greater than his sister... and came back as Zon-Kuthon, his mind warped by the very eldritch powers he'd sought to dominate. Upon his return, he murdered his and Shelyn's father, and attempted to kill her as well... but eventually, he was subdued. Shelyn now possesses his Glaive, in hopes that the tainted weapon might hold some key to returning her brother to his former self.
Or, more accurately... she possessed his glaive. For a long time, there were rumors that a facsimile of the weapon was kept by her faithful, acting as a sort of vessel that helped the goddess control the dark energies pouring from the blade. And now, those rumors have been verified... and in the worst possible way. The effigy blade has been stolen, and statues of the goddess around the world have begun to change overnight, the glaive in her hands crumbling to dust. And around the world, followers of the Midnight Lord rejoice... for when the facsimile is shattered, the god of Pain and Madness will once again have the strength to declare war on the gods.
Which is why the temple has turned to you, members of the Pathfinder Society. Your order's reputation for seeking out secrets and treasures is known all across the world, and it is their hope that you will be able to find and recapture the weapon that allows their goddess to keep the Midnight Lord at bay, before Zon-Kuthon's armies rend the heavens and earth in a war between gods...
In this campaign, your party is a charter-bearing chapter of the Pathfinder Society, and all your characters have at least one adventure under their belt. As such, you will start the game at 5th level, with the average player wealth for that level. In addition, you each will have one magic item (or magic weapon) costing 3000 GP or lower.
Let me know if this works for you.