A mysterious wizard, Gad, appears in the Dragon Castle deep in the mountains , trying to become the king by stealing the 'Dragon Heart', a jewel sealed with the mighty power of the little dragon king Arthur . Meanwhile, Crong, who accidentally absorbed the power of 'Dragon Heart' , turns into a giant Crong, putting Pororo and his friends in danger. Arthur, Pororo, and friends go to Dragon Castle by creating an invincible mecha dragon to recover their power from the villainous wizard Gad and save their friends ... . A fantasy action adventure of Pororo and his friends. Will he be able to protect Dragon Castle and his precious friends?