The King summons Thud and Blunder, a pair of nine-year-old knights, and sends them to Castle Kidnapt to "rescue" the five-year-old princess from the castle overrun by ogres--however it seems that it is the ogres who need rescuing.
Thud and Blunder are nine-year-old knights who set out to accompany a rather timid knight on a quest to obtain riches (without too much danger)--on the way they encounter a sick dragon who is quite willing to share his "gold."