Terminus

Sabotage!  The TARDIS is breaking up!  Thanks to the combined efforts of the treacherous Turlough and his evil master, the Black Guardian, the Doctor and his companions are in terrible danger.  The outside world has begun to break through and Nyssa has disappeared.  Can the TARDIS’ fail safe mechanism save them all by docking with another ship?  Unlikely, when the nearest vessel is a carrier of plague victims destined for the infamous Terminus, the time-bomb planet ticking at the center of the universe…

• "Terminus" is the fourth story of the 20th anniversary season of Doctor Who.   Each story within this season features the return of one of the Doctor's former adversaries.

• This adventure is the second in a trilogy of stories centering around the Black Guardian's attempts to destroy the Doctor as revenge for thwarting his plans to control the Key to Time.  The first story in this trilogy is "Mawdryn Undead" while the final one is "Enlightenment."

• This story also sees the departure of the Doctor's companion, Nyssa. 

• For some strange reason (I can't imagine what) Nyssa's clothing in her final story continues to fall off of her throughout the story.  She is left with nothing but her slip by episode 3.  I wonder why Adric or Turlough never had that same problem?