Sphinx:
1. The androsphinx who has been protecting the nearby town has gone missing, and the locals are worried. Is there some terrible hidden evil that has killed or captured him, or has he just skipped the town?
2. A gynosphinx shows up, doing her damnedest to find the said androsphix. If the characters are investigating the missing sphinx, she insists that she be allowed to join them. If not, she will hire them to do just that.
3. Criosphinx twins, fairly loaded with gold and jewelry, appear soon after, looking for the gynosphinx looking for the androsphinx. They are boastful, boorish and become very fidgety whenever the gynosphinx is mentioned...
(Basically, this is typical sphinx courtship...)