All Aaron wants in life is to finish his degree, have a family, and work a steady desk job with a good work-life balance. And he's going to do that no matter how many times aliens invade the world.

After being shown a terrible future for Gallifrey by the Daleks, the Doctor must find a way of removing Rassilon as Lord President. Meanwhile, the Master has to escape from a primitive world, a plague runs riot in the lost city of Nalsatti, a rebellion breaks out, and a forgotten Time Lord asks for help to ensure Gallifrey's future survival.

The Cybermen are turning desperate. They need to repopulate, and fast. As a result, they turn to an unlikely ally to save them. But can he be trusted? And how will the Doctor deal with the upcoming crisis? Or is this just one world saving attempt too far for him?