Chicago February 14th 1929. Al Capone finally establishes himself as the city's boss of organised crime. In a north-side garage his hoods, dressed as policemen, surprise and mow down with machine-guns the key members of Bugs Moran's rival gang. The film traces the history of the incident, and the lives affected and in some cases ended by it.

A group of scientists travel to a remote island to study the effects of nuclear weapons tests, only to get stranded when their airplane mysteriously explodes. The team soon discovers that the tests have given rise to crabs mutated into intelligent, impervious, telepathic giants intent on increasing their numbers by breeding, then travelling to populated areas to feed, and which do not intend to be stopped by their discoverers.

An agent from a distant planet has been sent to earth to ship large quantities of blood to his world, where a plague is ravaging the populace. He comes equipped with an interstellar matter transmitter, telepathic mind-control powers, and deathray-shooting eyes. Because he is also affected by the blood disease, he gains control of the town's physician and has him place a nurse at his disposal, while he collects live humans for fresh blood; but gains the nurse's suspicions, along with those of her boyfriend - a town police officer.