Series / K-9 and Company
"Without a doubt the most 1980s sequence ever committed to film – if you want to see where everything went wrong in that era just stick these titles on…Poor Lis Sladen is made to look as though she is blissed out on wine wandering around the country in her metro, occasionally getting out to jog along the country roads and pull down a paper and stare into the camera as though she really is sizzled."
Doc Oho on the opening titles

Airing on December 28, 1981, a week before Peter Davison's debut as the Fifth Doctor, this little special brought back Doctor Who fan favorites Sarah Jane Smith and K-9.

Although K-9 and Company was conceived as a spinoff of Doctor Who, it wasn't picked up, airing as a single special, also called "A Girl's Best Friend". Nonetheless, it is part of the Whoniverse Canon and many elements of it define the character of Sarah Jane Smith after her departure in "The Hand of Fear". More than 25 years later, a second, more successful spinoff for Sarah Jane was made in The Sarah Jane Adventures, with K-9 making occasional appearances. Subsequently, K-9 also got his own show. (However, some of these stories feature different K-9 robots - the K-9 of the solo series is Leela's K-9 from "The Invasion Of Time".)

Sarah Jane Smith spends the Christmas holiday at her Aunt Lavinia's house in Moreton Harwood to watch her ward, Brendan Richards. In the house, Sarah Jane spots a large crate that was left in the attic for a few years. Inside is K-9 Mark III, a present from the Doctor.

There's also a cult going around doing nasty cult stuff, like kidnapping Brendan. Sarah Jane and K-9 investigate and find out that almost everyone in town is a part of this cult, called the Cult of Hecate. At night, the Cult of Hecate prepare Brendan as a sacrifice for the Winter Solstice, but Sarah Jane and K-9 save him just in the nick of time.

That's pretty much it really. Can you imagine what a full series would be like?

K-9 and Company provides examples of the following tropes: