K-9 and Company: A Girl's Best Friend (1981)

One time companion of the Doctor, Sarah Jane Smith returns to Earth and carries on with her journalist career. Now, in 1981, she has managed to rebuild her career and has come, a matter of days before Christmas, to her aunt Lavinia's (a famous scientist) house in the sleepy English village of Moreton Harwood to write a book and to rest after her world-travelling assignments. However, her journalist's nose sniffs out another mystery when she arrives to find Aunt Lavinia gone, and nobody knows where she is, but the local rumour is that she was the victim of a local witch coven. Worshipers of a pagan goddess Hecate gather to celebrate a festival by ritually murdering a friend of Sarah's. She needs help - and she gets it from a box from her friend "The Doctor." Inside the box is a metal robotic but almost human-like talking dog called K-9 that is built for Sarah Jane personally and together Sarah and K-9 sets out to solve the mystery and stop the killing of Sarah's friend.