summary from http://en.wikipedia.org/wiki/The_Crimson_Horror
In 1893, Silurian Madame Vastra, her human wife Jenny, and their Sontaran butler Strax investigate “The Crimson Horror”, a mysterious cause of death in which victims are found with red skin. Superstition states that the retina retains the image last seen by the person (an “optogram”), and they are shocked to find that the latest victim had seen the Doctor. They travel to Yorkshire, where Jenny infiltrates Sweetville, a community led by Mrs Gillyflower and Mr Sweet, who is not seen. Mrs Gillyflower preaches about the coming apocalypse to encourage people to come. She has a daughter, Ada, who is blind because she had been beaten by her late father, according to Mrs Gillyflower.
Jenny discovers the Doctor, who is chained up and exhibits red skin and a stiff stature. The Doctor enters a chamber to reverse the process, and explains to Jenny that he and Clara had arrived and discovered the mystery of “The Crimson Horror”. They had joined Sweetville to investigate, but learned that they were to be preserved to survive the apocalypse. The process did not work on the Doctor because he was not human, and was saved from being destroyed by Ada, who affectionately calls him “my monster”. The Doctor finds Clara and reverses the process on her. Meanwhile, Vastra recognises that Sweetville is using the venom of a prehistoric red leech. The Doctor and Clara confront Mrs Gillyflower, who reveals that she plans to launch a rocket to spread the poison all over the skies. “Mr Sweet” is also revealed to be a red leech that has formed a symbiotic relationship with Mrs Gillyflower. The Doctor berates Mrs Gillyflower for experimenting on Ada to get the preservation formula right. Ada, overhearing this, angrily advances toward her mother, but Mrs Gillyflower holds a gun to Ada’s head and heads into the rocket silo, which has been disguised as a chimney.
Mrs Gillyflower launches the rocket, but Vastra and Jenny reveal themselves with the vat of poison that they have removed from it. Mrs Gillyflower turns on the Doctor, but Strax appears at the top of the chimney and shoots at her, causing her to tumble over the staircase. As she dies, Mr Sweet abandons her. In rage, Ada strikes the leech with her cane. The Doctor and Clara say goodbye; Ada says that she is looking forward to finding new opportunities in life. Vastra and Jenny ask about Clara, as they had previously met a Victorian version of her in “The Snowmen”, in which she died. The Doctor does not wish to explain, however.
The Doctor drops off Clara in modern-day London. When she returns home, she finds the two children that she babysits for, Angie and Artie, have discovered photos of her on the Internet from the past, including one that she does not recognize of herself in Victoria London (“The Snowmen”). They assert she must be a time traveler and threaten to tell their father if she does not take them on a trip.
Discuss