One Thing: Lair of the Winter Wyrm
"Lair of the Winter Wyrm" by Greyface
One thing I love about this OPD is the use of betrayal throughout. The first betrayal is evident (at least to the game master) when we learn the letter that Princess Nisal is delivering to a dragon states that she is to be sacrificed. This was sent by her father, and I do not believe the princess is aware of the letter's contents. The theme of betrayal does not end here, in fact it has only just begun, and will likely affect the player characters before the adventure is complete. Get it here.