As William turns twelve, he wonders if Jason is still his best friend. In the pa
st year, Jason has grown a foot taller, while William is still a shrimp. When Ja
son challenges William to "jump the trains," William is terrified. How else can
he prove himself to Jason? William gets his answer when his former housekeeper s
ends him a magic token that once again transports him to Sir Simon's castle in t
he Middle Ages, this time with Jason. There the two friends face a dangerous arm
y of rats and their gigantic leader. Once before, William was a hero in Sir Simo
n's day. Now it's up to William to destroy the rats and save the kingdom in the
final battle for the castle.