UFOs appear on Earth, and people who actually see them suddenly find that their blood has turned blue. Soon panic and hysteria result in the new "blue-bloods" being persecuted by the rest of mankind, and eventually certain all-too-familiar measures begin to be taken against them.

A drive-in favorite, this sci-fi classic follows teenagers Steve and his best girl, Jane, as they try to protect their hometown from a gelatinous alien life form that engulfs everything it touches. The first to discover the substance and live to tell about it, Steve and Jane witness the blob destroying an elderly man, then it growing to a terrifying size. But no one else has seen the goo, and policeman Dave refuses to believe the kids without proof.