Death stalks the fogbound streets of Victorian London. Young women are going missing. Horribly mutilated bodies are found floating in the Thames. And criminal gangs terrorize the innocent. At the heart of this tangled web sits the mysterious Li H'sen Chang, sorcerer and hypnotist, and his grotesque sidekick, the all-too-lifelike ventriloquist's dummy, Mister Sin. The Doctor dons deerstalker hat and cape to seek out the sinister force lurking in the shadows of the metropolis.