Josephine Grant had only just completed a brief training period as a spy when she had her uncle use his influence to assign her to UNIT. Assigned to be the Third Doctor's assistant, Jo's knack for getting into trouble was immediately apparent.
Ditzy, but fiercely independent, Jo's confidence and bravery grew with experience. As well as facing a series of adventures on Earth, during the Doctor's exile, she also visited a number of alien planets, including Skaro and Peladon.
After disappointing a series of would-be suitors, Jo finally fell in love with Eco-warrior Professor Clifford Jones, and left the Doctor to explore the Amazon with her new fiancé whom she later married and had seven children and twelve grandchildren.
She was reunited with The Doctor in his Eleventh incarnation when UNIT informed her of his suspected death.