Nine Lives Are Not Enough is a sequel to the thrillers The Manchester Vendetta and the Cheshire Conspiracy in which Guy and Julie Manners are sought by their nemesis, Eva Howells, who is seeking to avenge the death of her lover, Max Boyston, the former head of the Internal Security Service in Manchester during the dictatorship. Imprisoned in a high-security gaol, she is rescued by sympathisers following an emergency appendectomy operation and takes refuge in a safe house at the Cross Keys Caravan Park near Hartington in the Peak District with the intention of locating an escape line to leave the country. MI5 officers Bill Mackenzie and Emma Sanderson seek to hunt her down with the assistance of Guy Manners and take down the escape line by infiltrating their agent Maggie Irvine into the organisation. The destruction of a safe house in Maidenhead and the interrogation of its staff by MI5 at its Cliveden House interrogation centre leads to a final reckoning with Eva Howells and the elimination of the terrorists escape line.