A Galactic servant, that's what you feel like at the moment. You'd think that the Timelords would be pleased that you were not only responsible for discovering that Morbius' brain had been secretly kept alive, but that you were instrumental in destroying the revived villian. Do they offer you their gratitude? No, they merely point out that you left the Brain of Morbius on Karn and demand that you retrieve it and bring it back to Gallifrey. That's gratitude for you.
However, as you value your own freedom, you really don't have much choice but to do as the Timelords request. At least they gave you the coordinates for Karn, but you did notice that they refused to give you return coordinates for Gallifrey, saying you'd receive them once you'd procured the brain. So much for Gallifreyan hospitality...
Your thoughts are interrupted as you hear a familiar thud. The TARDIS has landed on Karn.
Notes
An unofficial sequel to the Doctor Who TV story The Brain of Morbius.