"Journey to the Centre of the TARDIS" is the tenth episode of the seventh series of Doctor Who, starring Matt Smith as the Eleventh Doctor and Jenna-Louise Coleman as Clara Oswald. It was written by Stephen Thompson, who had previously written the somewhat underwhelming Curse of the Black Spot.
The episode's title is a very fitting description. The TARDIS is accidentally breached by the actions of some space salvagers, and with the TARDIS in distress and with the Doctor separated from Clara, events look like they are heading for disaster. The Doctor and the salvage crew must journey to the centre of the TARDIS to stop the TARDIS from exploding. But mysterious and frightening monsters are prowling the TARDIS corridors, making the operation more dangerous. And wandering into the TARDIS' gigantic library, Clara finds a book on the history of the Last Great Time War.
Like many fans, my journey through Doctor Who has been up and down, with my reaction ranging from "this is incredible" to "this show makes no sense and I've seen this plot five times before". This episode was not new, but it was spectacular. There was an immersiveness to it that I hadn't experienced for a while. An entire cycle of the plot with suspense and resolution was finished, and we were not yet half way into the episode. The episode also has some gorgeous scenery, showing parts of the TARDIS that have been hinted at before: the library, the swimming pool, and even The Eye of Harmony. The shots are gorgeous and it really does feel like being in a pandimensional spaceship.
This episode both restored my faith in Doctor Who, and piqued my interest in the continuing story arcs that Doctor Who finds itself enmeshed in right now.