DOCTOR WHO IN DETAIL

As a spaceship hurtles towards a small planet the pilot, Cass, is desperately calling for help. The computer misunderstands Cass's request for help, and instead thinks she's injured. Cass says she's crashing, not injured, and that she's doesn't need a doctor. As she keeps trying to send a distress signal a man appears behind her - saying he is a doctor.

Cass tells the Doctor that the rest of the crew have teleported off. The Doctor then welcomes her aboard his ship, and leads her towards a Police Box located at the back of the ship. Cass is unsure, but the Doctor tells her it is bigger on the inside.

On hearing that Cass realises that the Police Box is a TARDIS, and that the Doctor is a Time Lord. Even though he swears he is not part of the war, and never was, Cass doesn't trust him. She steps out of the airlock and deadlocks the door, leaving the Doctor and the TARDIS inside. The Doctor says he is not leaving without her. Cass tells him that if he doesn't he will die in there along with her - the best news she has had.

The ship crashes on Karn, and the Sisterhood is waiting. They knew that one day the Doctor would return, even as a dead body after the crash.

When the Doctor awakes he sees a Priestess of the Sisterhood who tells his they are still trying to extract Cass from the wreckage, and that they have restored him to life; he has a little under four minutes of life left. After a few moments the Doctor realises he is back on Karn. Priestess Ohila tells the Doctor that their elixir could save him - and trigger a regeneration.

The Doctor wonders why the Sisterhood would offer him life, and Ohila tells him that the war between the Daleks and the Time Lords threatens all reality, and that he is the only hope left. The Doctor tells Ohila he helps where he can, but he calls himself a Doctor; he will not fight. But the one thing the Universe needs is a healer.

Ohila offers the Doctor a potion that will allow the Doctor to regenerate, and allow him some choice over the next regeneration. The Doctor chooses 'Warrior', and orders every one out as he drinks the potion and regenerates.