Okay, so created this worthy quest using random dice rolls and some slight filling in of details:
Lunatic Liaison
The PC is approached by a former teacher, a NE half-elf female ascetic monk priest (choose your deity, I can suggest one for FR if you are using it). One of this monk's acolytes has become raving mad, and she is requesting the PC to do something about it. In her midnight meditations, it has been revealed that the source of the the madness was the result of the acolyte traveling to some strange location in the wilderness. The PC must escort the lunatic NPC back to this location, and reverse the effect, resulting in a return to his sound mind of before. How the PCs accomplish this is half the fun. The acolyte is a LE human male monk, and has taken a vow of poverty. In his lunacy, he has taken to chewing on all kinds of objects, leather, metal, and has suffered damage to his tongue, teeth, and lips as a result, and it has affected his speech, as well as his ability to communicate in a normal fashion.
The adventure location is set in the wilderness, a nearby swamp/bog, which contains an ancient ruined keep. While exploring the keep, the errant monk delved too deep, and unearthed the catacombs beneath the keep. There, he disturbed the soul of an ancient cleric, still alive in undeath. This evil being cursed the acolyte with madness, mistakenly (in it's own madness) thinking him to be the source of his ruin, and essentially was seeking revenge. Not an outright death, but a madness that would wreck his life (so far working as intended). Attempts to remove the curse have failed, and the curse can only be removed by destruction of an object in the possession of the ancient cleric, an electrum dagger with a black pearl in the pommel. It is up to the PC to discover all of this, recover the dagger somehow, and destroy it in the presence of the mad monk, thus restoring his right mind.
I'm hesitant to give any further details at the risk of a railroad plot. But that should give you a bit of an outline to go from. Also, has the convenient twist that the two primary NPCs are evil aligned, and may be at odds, or in the fringes of the society or town where the PC is at present, thus driving their need for adventurers. Go, go random dice rolls!