Parts: 6
Writer: Robert Holmes
Airdates: 26 February 1977 - 2 April 1977
Production Code: 4S

Doctor: fourth
Companion: Leela

Megalomaniac of the Week: Magnus Greel

Story: The Doctor brings Leela to Victorian London, intending to impart a bit of culture to her by way of the theatre - currently playing, the oriental mystic Li H'sen Chang. Their theatre trip is ill-fated, however, as a dying scream pierces the air. When the Doctor and Leela hurry to the scene, they are attacked by a group of black-clad assassins. Leela manages to capture one as the police arrive.

The man is a member of the Tong of the Black Scorpion, a dangerous Chinese gang. The Doctor attempts to extract information, and even the great Li H'sen Chang offers his assistance. But Chang is not the upright man he seems to be, and slips the Tong member a pill of concentrated scorpion venom while the others' backs are turned. With their only lead dead, the Doctor and Leela head back out onto the streets - and into the sewers of London, where they discover a horrific menace.

London has been plagued by multiple disappearances of young girls, making some wonder if the Ripper has re-appeared. When the Doctor learns that one of these girls saw Chang shortly before she vanished, his suspicions are further aroused. What is the connection between Chang and the missing women? What vile creatures stalk the darkened streets and dank sewers of the city? And, most importantly, what is the phantom-like creature lurking in the basement of the theatre?