Sarah Jane Smith visits her Aunt Lavinia, who was occasionally mentioned but never seen in "Doctor Who". When she arrives at her aunt's house, though, she finds that her learned relative has left early for a lecture tour in America, Christmas notwithstanding. Sarah is thus left disappointed by the prospect of another holiday without family. Lavinia's ward, Brendan Richards, breaks her moment of reflection on her aunt's sudden disappearance. After picking him up from the railway station, they return to the house and discover a large crate that has been waiting for Sarah for a number of years. When they open it, they discover a mechanical dog named K9. Upon activation, it tells Sarah that it is a gift from the Doctor.