Fun fact: The first draft of this week’s episode was titled “Prisoner of the Sun”
4×03 Twinkle, Twinkle: The Doctor wants to observe a rare coronal mass ejection from an unusual star when another ship nearly collides with the TARDIS, forcing it to crash land. The Doctor and Sammy find themselves in Heliopolis, an impossible city built on the surface of the star itself. With a damaged TARDIS and only forty minutes until the coronal mass collides with the city, can the Doctor and Sammy save Heliopolis, and themselves?