A Victorian mystery for the time-travelers—Topher and his amazing cat—to resolve Topher's cat, Ka, has time-traveled again, leaving him the clue "CAppeLLis." Following her, Topher finds himself in Victorian London where disease is rife and the Thames is clogged with stinking sewage. Topher discovers a plot to kill Joseph Bazalgette, the man who is trying to save the city. Determined to foil it, Topher must first escape from an arch-criminal and his den of thieves. This well-researched and exciting adventure is a great read for Doctor Who fans.