A strange message alerts Steed, Purdey, and Gambit to something strange going on. While Steed does his own research, Purdey and Gambit set out to help shed some light on the situation. However, the reality of the case is that due to a seventeen-year-old open case and a bout of amnesia, the legendary traitorous White Rat has at last begun to operate again. And Purdey is in imminent danger from her own romance.

A bizarre series of deaths of high-ups in the government becomes the business of Steed and his colleagues when a personal friend of his becomes one of the deceased. However, due to suspicion from the delicate nature of the case...apparently people are being duplicated by an unscrupulous firm...Steed, Purdey, and Gambit all go off on their own and make individual progress into the case. However, it seems that the situation is too far-reaching and confusing for each alone. They must work together and figure out quickly, who's who and what's what, before they themselves become the next targets.