Linx: We're sworn enemies, Doctor. Why should you help me?
Dr. Who: Because I want something from you. If you will let me de-hypnotise the people and send them home, and help me capture Irongron and his men, then I will assist you in the repairs to your spaceship. The weapons you've made for Irongron you can leave here in the castle. When it's empty, you can take-off, destroying castle and weapons at the same time. Alright, Commander Linx, what do you say?
Linx: You wish for my answer, Doctor?
Dr. Who: I do.
Linx: Then here it is. [shoots the Doctor]