The Doctor fires, killing the giant rat and saving Leela. She apologizes for failing to kill Weng-Chiang. She offers to take him back but the sound of more rats indicate it’s too dangerous to go to the theatre, so they retreat back to Litefoot’s boat.
As Jago prepares for the night’s show, Chang confronts him and Jago admits he doesn’t remember what they discussed. Chang reminds him of his offer and notes he will be appearing that night without Mr. Sin.
Leela describes what happened and the Doctor recognizes the process as organic distillation, but warns that it’s highly dangerous. Litefoot brings Leela new clothes and she goes to put them on. The Doctor is more interested in the cabinet and notes it can only be opened with a key of the proper molecular combination. He explains to Litefoot that Weng-Chiang arrived in the cabinet, a gift to Litefoot’s family from the Queen. Leela arrives in her new clothing and the Doctor promises to take her to the theatre that night.
Jago and Casey discuss preparations for the night’s show and the Doctor’s presence. Chang overhears them and prepare a revolver.
The Doctor and Leela are playing draughts as Litefoot tells them their carriage is there. The police are watching Litefoot’s house and the Doctor warns that Chang and his men will do whatever is necessary to get the cab. They leave, walking past the laundry basket left earlier by the Chinese laundrymen.
Chang goes to see Weng-Chiang as the latter packs his equipment in his bag. The magician tells his master that he plans to publicly humiliate the Doctor and then kill him. Weng-Chiang says what Chang does is no longer of interest and he should do what he wants.
Jago spots the Doctor and Leela in the upper balcony and goes to see them, telling Casey to go down to the cellar and prepare for the show. The Doctor assures Jago that he has everything under control. He does note that he doesn’t have any men in the audience, much to Jago’s bemusement. Meanwhile, Litefoot checks to make sure the police are still on patrol outside his house.
Leela and the Doctor watch the opening act and the Doctor notes that Weng-Chiang will come looking for them. Meanwhile, Casey prepares for Chang’s act and Weng-Chiang grabs him.
Jago introduces Chang’s act and the magician begins by tossing the Doctor a deck of cards and inviting him to choose a card. The Doctor selects the Ace of Diamonds and places it back into the deck. Chang takes a gun and prepares to shoot the Ace of Diamonds through the rest of the cards. The Doctor calmly holds the deck out and Chang fires. The Doctor is unharmed and the Ace of Diamonds has a bullet hole in it. Chang invites the Doctor down to help with his next illusion, the Cabinet of Death.
Tong members approach Litefoot’s house and kill the policemen on patrol. Inside, Mr. Sin emerges from the laundry basket
The Doctor enters the Cabinet of Death but quickly slips out the back. Chang, bemused, continues and has his assistant Lee take the Doctor’s place. He then skewers the cabinet with swords Lee slips out through a trapdoor in the base and discovers Weng-Chiang waiting for him. Above, the Doctor assists Chang, who removes the swords and opens the cabinet to reveal… Casey, dead of a heart attack. Jago drops the curtain and Chang slips away.
In the basement, Chang calls out to his master and discovers that he’s been abandoned. The Doctor arrives and stops Chang from taking poison to kill himself and join his forefathers. The Doctor demands to know where Weng-Chiang went and Chang admits he failed his master. The magician insists that Weng-Chiang came like a god, appearing in a blazing cabinet of fire. Weng-Chiang was ill for many months and Chang, a humble peasant, nursed him back to some semblance of health. The emperor’s soldiers took the cabinet and he and Weng-Chiang have searched for it ever since. Jago comes down and Chang takes advantage of the distraction to slip into the sewers and seal the portal behind him. The Doctor warns that Chang has gone to see his ancestors. Giant rats close in on the magician as he wonders, his mind shattered by his master’s abandonment.
As the rats drag Chang away, Leela finds the clothing of the missing girls. She notices the organic distillation machine has disappeared and the Doctor concludes Weng-Chiang will start up the whole thing again. He warns that the more energy Weng-Chiang absorbs, the greater the distortion of his metabolism. The rats were used to gauge the strength of the psionic amplification field. The Doctor says they need to head back to Litefoot’s house and guard the Time Cabinet.
At Litefoot’s house, the professor lies unconscious as Weng-Chiang and Mr. Sin depart with the Time Cabinet.