The Doctor and Leela return to Litefoot’s house and discover the dead policemen. They realize that Mr. Sin was smuggled in via the laundry basket and find Litefoot as he wakes up. Litefoot explains that the Tong attacked and took the Time Cabinet. The Doctor realizes that Mr. Sin is the Peking Homunculus, created in the Ice Age in the year 5000 for the Commissioner of the Icelandic Alliance. The automaton had one organic component, the cerebral cortex of a pig. The pig part took over, attacking the Commissioner and almost setting off World War VI. Somehow Weng-Chiang came from the year 5000 with the Homunculus, but the time travel he used is a dead-end and highly dangerous.
In his secret lair, the Tong members bring the Time Cabinet to Weng-Chiang. He prepares for his departure and demands the bag and the crystal key inside, but the Tong members explain that it was left behind. Weng-Chiang turns on Chang’s former assistant, Lee, and demands that he take scorpion venom. Lee has no choice but to obey and dies a painful death, while Mr. Sin laughs in triumph.
The Doctor discovers where the laundry basket came from. He warns that Weng-Chiang has no idea what he’s doing with the Zygma energy that he used to travel through time. If Weng-Chiang tampers with the beam at its highest tension, it could destroy half of London. The Doctor and Leela go to investigate.
Jago examines the cellar and plans a tour. He notices a carpet bag and leaves with it, while someone claws their way out of the sewers behind him. Jago goes to Litefoot’s house to attempt to contact the Doctor. Litefoot tells him that the Doctor has departed and Jago shows him the carpet bag. Litefoot wonders if someone might return for it and says they should watch the theatre and nab Weng-Chiang on their own. Jago tries to beg off but Litefoot convinces him to come along.
The Doctor slips into the laundry and discovers it conceals an opium house. Chang is there, taking opium for the pain at the loss of one leg. He speaks of the House of the Dragon and explains he woke up in the rat’s larder of putrefying human remains. He slipped away, cursing Weng-Chiang, and vowed to kill his former master. Delirious with pain, Chang speaks of having been honored to perform for the Queen and speaks obliquely of the House of the Dragon, saying to beware the eye of the dragon. Chang hallucinates seeing his ancestors come to greet him and passes away.
The Tong members return to tell Weng-Chiang they failed to find the carpet bag. He goes to the window and sees Litefoot and Jago. He concludes they have the bag and tells his men to capture them. Outside, the duo considers what to do and is soon captured. They are brought before Weng-Chiang and try to bluff. Weng-Chiang doesn’t believe them and chokes Jago until Litefoot tells him the carpet bag and crystal key is at his house. Weng-Chiang orders them locked up with the other prisoners.
The Doctor and Leela return to Litefoot’s house and find a note from Jago explaining that they found the carpet bag at the theatre. Inside is the key, a trionic lattice necessary to open the Time Cabinet. Leela suggest they go to the theatre to find Litefoot and Jago, but the Doctor realizes they’ve been gone a long time and they should wait for Weng-Chiang to come seeking the key. Leela starts sharpening her knives.
Jago and Litefoot are locked up with two of Weng-Chiang’s intended victims. Litefoot begins to lose hope but Jago assures him that the Doctor will find them. They locate a dumbwaiter and Litefoot suggest they climb up to the dining room and escape. The two men proceed with their plan but the Tong members are waiting for them at the top and recapture them.
The Doctor and Leela split up to prepare for Weng-Chiang’s arrival. Weng-Chiang slips through the drapes and ambushes Leela, attempting to drug her with chloroform. As she struggles, she rips aside his mask to reveal a hideously distorted visage.