The Doctor and Ace are on the trail of a monster that not only knows their every move but appears to be able to anticipate their actions too. The head of the far right New Brittania party survives an assassination attempt, but the Doctor suspects there is far more to the affair than the failed slaying of a politician. 

As he and Ace fight their way through the prejudices which blind everyone touched by a very particular monster, they face the prospect of the entire world being plunged into a bitter war of mistrust and mutual loathing...