One breath of a nerve gas will kill you ... and so will a drop of it through the skin. One plane-load of it could wipe out the people of a city like Leeds without destroying the buildings. One plane flying along the coast of Britain could spray enough germs in one night to infect much of the population of London ... they would not know they had been infected and they would all become ill at about the same time. What are the facts behind statements like these? How have chemical and biological weapons come to equal nuclear weapons as potential mass killers? What protection is there against them? What, if anything, prevents their being used? What goes on inside Britain's secret research centre at Porton Down in Wiltshire? Tonight's documentary film sets out to provide an answer to these questions. Series editor, MAX MORGAN-WITTS Narrator, ALAN DOBIE