Dreaded news from the Sirus sector! Like a recurring nightmare, the monstrous menace has returned. With the memory of their last blitz of terror all too fresh, the hideous Vollchon battle machines once more threaten the galaxy. Only Professor Klein, genius astrophysicist, possesses the esoteric knowledge to foil their quest for domination. But Klein is in danger, feared dead! And only one starship stands the slightest chance of saving him. The call for help goes out to the far corner of Sirus sector – to the colossal Starship Essex.