While investigating the disappearance of several young women and the grisly murder of a cabbie, the incomparable Doctor Who (Tom Baker), assistant Leela (Louise Jameson) and Professor Litefoot (Trevor Baxter) encounter their most sinister enemy to date. Magnus Greel is a war criminal from the future posing as the ancient Chinese god Weng-Chiang. Victorian London's dark streets are the setting for the Doctor's battle against his most evil foe.