Mark is up for promotion at work, but loses out to Sophie.
Injured by the Orgrons, the Doctor asks the Time Lords to send the TARDIS after the Daleks. Leaving him to sleep and recuperate, Jo goes to explore the planet Spirodon.
The Doctor awakes from his coma, befriends some Thals but is captured by the Daleks.
The Doctor and the Thals escape from the Dalek city and the Doctor is delighted to find Jo is alive. But the Daleks are preparing deadly bacteria to kill all life on the planet.
In the Dalek city, the Doctor breaks out of his prison cell and joins forces with the Thals. With the Daleks in pursuit, he is forced to improvise a daring escape plan.
