An Israeli scientist invents a machine which is able to exchange the bodies of people. No one in Israel can see any use for it but the Minister of Science in Britain cannot wait to get his hands on it. Ultimately it is sold and brought to England to a laboratory at Lytham St. Annes. The great advantage of the invention is that while the bodies are exchanged, the heads and brain remain the same.Lancaster jail is a tough place to be incarcerated. It contains five hundred prisoners all serving life sentences and is under strict control. Then the Government decides that, with the new invention, they intend to exchange prisoners at the jail with very old eminent people who contributed greatly to society, thereby extending their lives by thirty, forty or fifty years. It mean that a thirty-five year old prisoner would exchange his body with an eighty-eight year old man. The reasoning was that the inmates in the prison were simply rotting away uselessly.