Barney's friends are building a sand castle in Derek's backyard when who else but Barney himself appears! With the use of imagination, Barney takes the group on a fun-filled adventure to a real castle. On their journey, they travel through a magical forest where they discover a new friend -- Twynkle the Elf. Once Barney and his young friends reach the castle gate, everyone plays with magical horses and the royal maypole! Then it's time to enter the castle and meet the king, who has a special favor to ask. Soon, Barney and his friends are joined by Baby Bop for songs, a tea party and other castle fun.