A mysterious epidemic grips the city! Everywhere, men and women drop suddenly into a nameless coma. What causes the affliction? Scientists are baffled by the disease! Even gifted Doctor Elefun of the famed Institute of Science is at a loss until Astro Boy-quite by accident-discovers a strange species of horse-fly near the names of various victims. His hunch proves correct: the flies are mutants-deadly cousins of the common house fly, made poisonous by exposure to atomic radiation. But what Astro Boy himself failed to realise at first, was that the lethal little insects were actually being bred by a ruthless master criminal whose dreams of power would proceed unchecked, unless an enemy could be found who was immune to the bite of the flies. Astro Boy becomes that enemy. To wipe out the breeding ground ofthe flies, Astro Boy must battle a formidable array of robot guards.