A mutated biological agent escapes from Porton Down weapons testing establishment outside Portsmouth, England. Superficially, the mutant appears to be a butterfly. The story revolves around a couple of University lecturers who stumble unwittingly on the agent, thinking it a new species. Through their research, the authorities are alerted to the possible publication of its origin and take ruthless steps to prevent this. Murder, political intrigue and big-business machinations occur against a background of increasing social awareness of danger and unrest, whilst a number of dedicated opponents of the system struggle for recognition of humanitarian values. Underlying the development of the characters and the action is an awareness of the interconnectedness of all life and a strong philosophical argument for the effects of inertia on ecological systems and on social conventions, no matter how violently these are disturbed.