Doctor Who: The Newbies Guide
The Brain of Morbius
This is the fifth story in Season 13.
The Fourth Doctor dresses in a rather bohemian outfit, notable for its long scarf. He is somewhat alien, willing to play the fool, and almost never gets on with authority figures.
Sarah Jane Smith is a journalist who, in The Time Warrior, sneaked into UNIT in search of a story and ended up accompanying the third Doctor on a trip to the middle ages. Sarah has subsequently become the Doctor's travelling companion.
Recurring and Historical Characters
The new character Morbius is identified as being one of the Doctor's people, the Time Lords. But you don't really need to know anything about them to understand this story.