In the first net plot book, there is a quick adventure idea summed up as: "Save the good dragon from the evil princess"
Some suggestions
Evil Princess intent on overthrowing her parents, but lacking the needed backing among the leaders of the army, has managed to locate an Arcane and purchase (with monies/items stolen from the kingdoms treasury) an amulet/ring/potion/item which allows her to control the dragon which for generations has helped protect the (select compass direction) borders and mountain passes of the kingdom from marauders and invading forces. The dragon under her control has been attacking outlying areas and the population is in an uproar. The forces of evil, alerted by the princess that her plan is beginning to bear fruit, are moving towards the kingdom. The king has suspicions, the general knows what's up, but can not take direct action against the princess, the court wizard is away at the time (arranged by the princess, false leads on an ancient artefact etc). The only hope for the kingdom is that heroes will arise and release the dragon from the princesses control, and bring to light the entire plot so that the king can banish her and make her younger sister the true and good heir. If the heroes should fail, the entire kingdom will be cast into a era of darkness and evil.