Sincline plans to dig below the Castle Gradam, capture Princess Fala, and plant a massive bomb to destroy the castle and the GoLion team in it. The drilling is causing massive earthquakes which alerts Shorty to the danger who investigates along with the help of a local boy Mario but are soon captured and strapped to the bomb themselves. The rest of the GoLion team must rescue them before taking on a giant drill-machine Beastman named Delta!