From the Introduction:
Castle of Blood is an adventure module for Fantasy Adventurers for Kids. It is designed for a party of three to five adventures, so the GM must play the role of extra adventures if there are not enough players.
A massive black castle sits on top of the mountaintop that overlooks the village of Valestein. The entire countryside surrounding the castle is shrouded in eternal night and all its villagers cower in fear wondering who will be the next victim. Every night a shadowy figure comes down to the village and leaves one of the villagers completely drained of all his or her blood. The adventurers must attack the dark castle and destroy the evil force that lies within. The entire castle is surrounded by deadly thorned vines that will kill anything that touches them. After talking with the villagers, the adventurers will find out that there is an ancient sewer system underneath Castle Valestein that might be a way inside.