To Catch a Rat - S1.E7

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.