I just finished up the episode and came up with the idea that Maisie was given a lot of attention during this episode. I know she was the main character for this episode and I keep hearing she is a guest star but at the end of the episode she had a moment when she was travelling through time since she is immortal and it seemed as if she was as important to the doctor as much as much as Clara is. Since I we know this is Clara’s last season on the show, It feels like Maisie possibly may be taking the role of The Doctor’s companion since she is now immortal and since The Doctor’s largest fear is traveling through space and time alone.
I really hope I’m wrong but it seems like it could be a possibility that Maisie becomes The Doctor’s new companion, with all the advertisements we see with Maisie in. Anyone disagree I beg of you. I don’t feel Maisie would make a great companion…