now masquerading as the Chinese god Weng-Chiang. The technology of the cabinet is unstable and has disrupted Greel's own DNA, deforming him horribly. This forces him to drain the life essences from young women to keep himself alive. At the same time, Greel is in search of his cabinet, which is now in the possession of Professor Litefoot. Mr Sin is also from the future but is a robotic toy constructed with the cerebral cortex of a pig. Greel tracks down the time cabinet and steals it, whilst concurrently the Doctor tracks Greel to the sewers underneath the theatre, aided by the theatre's owner, Henry Gordon Jago. However, Greel has already fled, abandoning Chang to the police. Chang escapes into the sewers, only to be mauled by one of Greel's giant rats. While the Doctor and Leela try to find Greel's new hideout, Jago comes across the key to the time cabinet. He takes it to Professor Litefoot's house, and there, after leaving the key and a note for the Doctor, the Professor and Jago set out to follow anyone coming around the theatre in search of the bag. However, they are captured. Meanwhile, the Doctor and Leela find Chang in an opium den, dying from his injury. The Doctor and Leela ask where Greel can be found, and Chang tells them he can be found in the House of the Dragon, but dies before he can give them the exact location. The Doctor and Leela return to Professor Litefoot's house. There they find the note and the key to the time cabinet. They decide to wait for Greel and his henchmen. When they arrive, the Doctor uses the key, a fragile crystal, as a bargaining chip. He asks to be taken to the House of the Dragon, offering the key in exchange for Litefoot and Jago's release. Instead, Greel overpowers the Doctor and locks him in with the two. Leela, who had been left at Litefoot's house, has followed them and confronts Greel. She is captured by Greel, but before her life essence is drained, the Doctor, Jago and Litefoot escape and rescue her. In a final confrontation, Mr Sin turns on Greel as the Doctor convinces it that Greel escaping in his time cabinet will create a catastrophic implosion. The Doctor defeats Greel by forcibly pushing him into his own extraction machine, causing it to overload and Greel