Series 1: The Daleks

This story introduces two tropes in Doctor Who, that of the TARDIS' navigational circuits malfunctioning and that of the supposed destruction of the Dalek race. In this case, instead of bringing its crew back to Earth, the TARDIS lands in a petrified jungle, and the Doctor has to try to fix their position by taking a reading of the stars. The Doctor insists they explore a futuristic city they spot beyond the forest but Ian Chesterton and Barbara Wright are not convinced. To force his companions to do so, the Doctor sabotages the TARDIS by emptying the mercury fluid links (although he later admits this was a ruse), forcing the crew to travel to the city in search of more mercury.

Inside the city, Barbara becomes separated from her colleagues, and is, in the iconic first episode cliffhanger, threatened by an unseen creature with a metal arm - the first appearance of a Dalek. Before long, the entire crew is captured by the Daleks. Susan is eventually sent to retrieve anti-radiation drugs from the TARDIS, where she encounters a second species, the Thals, who are at war with the Daleks. Susan attempts to broker peace between the two groups, and while it appears to work, the Daleks eventually betray the Thals, opening fire on them at what was supposed to be a peaceful exchange of food.

In the ensuing chaos, the Doctor and his companions escape with the Thals, and learn their version of the history of their planet. They also learn that the Thals are avowed pacifists. In order to save them from the Daleks, the TARDIS crew convinces the Thals of the importance of aggression and warfare, and manages to lead the Thals in a successful genocide against the Daleks. At the end, it is believed the Dalek race has been destroyed.

Cast
Doctor William Hartnell (First Doctor)
Companions Carole Ann Ford (Susan Foreman)
Jacqueline Hill (Barbara Wright)
William Russell (Ian Chesterton)
Guest stars
Alan Wheatley — Temmosus
John Lee — Alydon
Virginia Wetherell — Dyoni
Philip Bond — Ganatus
Marcus Hammond — Antodus
Gerald Curtis — Elyon
Jonathon Crane — Kristas
Peter Hawkins, David Graham — Dalek Voices
Robert Jewell, Kevin Manser, Michael Summerton, Gerald Taylor, Peter Murphy — Daleks
Chris Browning, Katie Cashfield, Vez Delahunt, Kevin Glenny, Ruth Harrison, Lesley Hill, Steve Pokol, Jeanette Rossini, Eric Smith — Thals

Production
Writer Terry Nation
Director Christopher Barry (episodes 1,2,4,5)
Richard Martin (episodes 3,6,7)
Script editor David Whitaker
Producer Verity Lambert
Mervyn Pinfield (associate producer)
Executive producer(s) None
Production code B
Series Season 1
Length 7 episodes, 25 minutes each
Originally broadcast 21 December 1963–1 February 1964

source: wikipedia