In the playroom, the Princess and Bona accidentally lose a ball that ends up in the Prince's pyramid made of blocks. Venturing after their toy, they're transported to a fantasy world and an ancient pyramid, where they don explorer personas! They outsmart a room of cunning traps and recover the ball, but the fun begins when the Prince, dressed as a comical mummy, chases after them. Just as they seem cornered, the mummy-Prince gets tangled in his own wrappings and falls, causing the pyramid to crumble. Shaken but unharmed, the children decide it's more fun to play ball together.