Ian and Barbara discover that the paralysed Bennett has gone missing from his cabin. The Doctor discovers the truth about Koquillion, but endangers his own life in doing so.

The Doctor follows the Master's trail to the circus. Meanwhile, the Master has used his hypnotic powers to take control of a plastics factory where he creates the deadly Autons.

Imelda Staunton was born in Archway, north London. Both of her parents were first-generation Catholic immigrants from County Mayo, Ireland, with her father coming from Ballyvary and her mother from Bohola. 

Staunton enrolled at the Royal Academy of Dramatic Art (RADA), and studied alongside Alan Rickman, Timothy Spall and Juliet Stevenson. She graduated two years later in 1976, then spent six years in English repertory. Staunton then joined the Royal Shakespeare Company, and in 1982, moved on to the National Theatre. 

Staunton has twice received an Olivier Award, Britain's highest theatre honour, one in 1985 for roles in two productions: A Chorus of Disapproval and The Corn Is Green and one for the 1991 musical, Into the Woods. She was nominated for her performance as Miss Adelaide in the 1996 revival of Guys and Dolls at the National Theatre

Staunton's first big-screen role came in a 1986 Bill Douglas film, Comrades. She then appeared in the 1992 movie Peter's Friends. Other early roles include performances in Much Ado About Nothing (1993), Deadly Advice(1993), Sense and Sensibility (1995) Twelfth Night (1996), Chicken Run (2000), Another Life (2001), Bright Young Things (2003), Nanny McPhee (2005), Freedom Writers (2007) and How About You (2007).

Staunton shared a Screen Actors Guild Award for Best Performance by a Cast in 1998 for Shakespeare in Love. In 2004, she received the Best Actress honours at the European Film Awards, the BAFTAs, and the Venice Film Festival for her performance of the title role in Mike Leigh's Vera Drake, which also won Best Picture. For the same role, she received Best Actress nominations for the 2005 Golden Globes and Academy Awards.

Staunton portrayed Dolores Umbridge in Harry Potter and the Order of the Phoenix (2007), She was nominated in the "British Actress in a Supporting Role" category at the London Film Critics Circle Awards.[14] Staunton reprised her role as Dolores Umbridge in Harry Potter and the Deathly Hallows Part One.

Recent film roles include 2008's A Bunch of Amateurs, in which she starred alongside Burt Reynolds, Derek Jacobi andSamantha Bond, and the character of Sonia Teichberg in Ang Lee's Taking Woodstock (2009). She will play one of the lead roles in the upcoming ghost film The Awakenings.

In 1993, she appeared on television alongside Richard Briers and Adrian Edmondson in If You See God, Tell Him. She has had other television parts in The Singing Detective (1986), Midsomer Murders, and the comedy drama series Is It Legal? (1995-8), as well as A Bit of Fry and Laurie season 4, episode 3. She was a voice artist on Mole's Christmas (1994). She had a guest role playing Mrs. Mead in Little Britain in 2005, and in 2007 played the free-thinking gossip, Miss Pole, in Cranford, the five-part BBCseries based on Mrs Gaskell's novels, and in the sequel to the series, Return to Cranford. She also supplies the voices of Ruby (a mouse) and Twiba (The Worm who lives in Big's Apple) in the Children's TV show Big & Small. In 2010, she appeared in the Halloween special of Psychoville as Grace Andrews, and became a recurring cast member in the second series (2011). In 2011, she had a guest role in Series 6 of Doctor Who playing the Voice of Interface in The Girl Who Waited

Steve Plytas was an actor who worked in British films and television.

Film roles include: The Moon-Spinners, The Spy Who Came In from the Cold, Theatre of Death, Oh! What a Lovely War, On Her Majesty's Secret Service, Revenge of the Pink Panther, Carry On Emmannuelle, Superman IV: The Quest for Peace and Batman.

TV credits include: The Avengers, Danger Man, The Troubleshooters, The Saint, Doctor Who (in the serial The Tenth Planet), Z-Cars, The Champions, Department S, Dixon of Dock Green,Fawlty Towers (as a chef named Kurt), Who Pays the Ferryman?, The Professionals, Minder, Strangers, The Two Ronnies and Tales of the Unexpected.

Sarah Kemp was best known from the long-running Australian television series Sons and Daughters, in which she played the character Charlie Bartlett between 1982 and 1987.

Born as Gypsy Kemp, when living in the UK she appeared in a number of programmes, often credited as Gypsie Kemp. As well as her appearance in Day of the Daleks, she also had roles in diverse shows such as Z Cars, Shoestring, Happy Ever After and The Benny Hill Show. In Australia she changed her name to Sarah before her long stint in Sons and Daughters; other appearances included G.P. and the tv movie Mercy Mission: The Rescue of Flight 771.

She died in Bellingen Hospital, New South Wales, following a long battle with lung cancer.