Fragments of a mysterious stone known as the Skull Stone are scattered across the globe. Once all four pieces are assembled, the location to the world's largest deposit of gold will be revealed. The villainous Doronbo Gang are searching for the Skull Stone. Standing in their way are Gan and Ai who become the masked heroes Yatterman-1 and Yatterman-2. The two are aided in their adventures by a large mechanical dog Yatterwan.