Publisher's Synopsis
Eminent scientist Emil Keller has developed a revolutionary new process for the treatment of hardened criminals. His invention, the Keller Machine, is being heralded as a major scientific breakthrough. But Professor Keller is in truth the Master, and the Keller Machine is much more than a mere machine. Soon the Doctor, Jo, the Brigadier and UNIT are involved in a bitter struggle with the Master, an alien mind parasite, and a diabolical scheme to plunge the world into a Third World War.
