An English professor decides that there are too many useless people in the world and invents a gas that will kill them off. But first they'll at least have a good laugh.

Leo McKern
as Professor Kerris Bowles-Ottery

Janet Munro
as Delia Brooks

Maxine Audley
as Clarinda Bowles-Ottery

Dennis Price
as Dr. John Hughes

Miles Malleson
as Dr. Woolley

Mervyn Johns
as Willie Pugh-Smith

Leonard Rossiter
as Dr. Fisher

Jennifer White
as TV Make-Up Girl

Patricia Jessel
as Mrs. Pugh-Smith

Duncan Macrae
as Dr. Brass