The Krotons

As the TARDIS door opens onto a barren planet, the Doctor steps straight into a struggle to destroy the merciless Krotons, the unseen rulers of the Gond people. Conditioned to obey by teaching machines, the Gonds put up no resistance until, with the Doctor's help, they discover exactly what has been happening to their best students.

Battling against the Kroton's vast scientific knowledge, the Doctor and Zoe must stop them turning mental power into pure energy. With a brave band of Gonds and Jamie prepared to fight to the end, it may be defeat for the Krotons, but ultimately it will be a test of knowledge that only Doctor Who can match . . .

• Watch for an amusing scene is episode 2 with the Doctor and Zoe taking an intelligence test.  Zoe passes with flying colors but the Doctor has a bit more of a difficult time with it.

• Also watch for Troughton to start to slur his two companions names together.  "Joey" instead of "Jamie, Zoe!"

• Philip Madoc (Eelek) makes his first of several appearances on Doctor Who.  He returned later that season playing the chillingly meek and quiet War Lord in Patrick Troughton's final story "The War Games."  He would later return and play the mad scientist Solon in "The Brain of Morbius" and as Fenner in "The Power of Kroll."

• This was the first story penned by prolific Doctor Who writer (and later script editor) Robert Holmes.  Holmes has written more Doctor Who stories than any other author.  To see a list of his stories click here.

• In 1981 this story was shown during the much hyped "Five Faces of Doctor Who" not because it was an excellent example of Troughton's era, but rather because it was one of the VERY few complete Troughton stories left.