An astronomer discovers a black cloud approaching the earth threatening to wipe out all life, but no one will believe him, because all world governments are too busy waging war. Meanwhile, the boy detective Kenichi (voice of Hiroshi Suzuki), the young Rock Holmes (voice of Kaneto Shiozawa), Shunsaku Ban (voice of Kousei Tomita) - (Mustachio) and others discover the Fumoon, a race of tiny, telikinetic humanoids who evolved in Australia, and have their own plans for dealing with the impending apocalypse.