Importance: This is the first episode where it is alluded to that the TARDIS has a form of consciousness.
Synopsis: The Doctor causes a small explosion while attempting to correct the TARDIS’s navigation circuits, rendering the Docter, Barbara, Ian, and Susan unconscious. Upon waking, Ian and Susan begin to suffer from slight amnesia and everyone begins acting strangely. Eventually, everyone becomes suspicious of one another and the Doctor accuses Barbara and Ian of sabotaging his ship.
Thanks to Barbara’s insightful clue gathering, they soon discover that the strange events are an attempt by the TARDIS itself to warn the crew that something is wrong. The Doctor traces the problem to a broken spring in the Fast Return Switch which has caused the TARDIS to head back to the beginning of time. After the switch is fixed, everything returns back to normal. The Doctor is then forced to apologize, and admit that he was wrong about Barbara and Ian.
Thoughts: Basically, the Doctor almost kills everyone because he got a button stuck on the TARDIS console. The TARDIS then has to warn them that something is wrong before they are destroyed. Good job, Doctor. While this might seem rather anti-climatic, some important things actually happen in these two episodes.
First, the TARDIS is revealed to have some form of consciousness, which the Doctor wasn’t even aware of. The TARDIS was able to warn them that something was wrong, which ended up saving their lives. The fact that the TARDIS has a consciousness comes up multiple times in Modern Who, so it’s interesting to see that the Doctor didn’t know that when he first stole the TARDIS. This whole adventure has been a learning experience for him, since he still isn’t totally comfortable with his abilities to even control where it goes. It’s been kind of a guessing game for him so far.
Second, the Doctor and Barbara form a new, closer bond by the end of the episode. The Doctor is forced to apologize to Barbara for suspecting her of sabotaging the ship and threatening to kick her and Ian out of the TARDIS. He is also forced to realize that he has underestimated Barbara this whole time. She is the reason they figured out that the TARDIS was talking to them, and she is basically the reason they are alive. He even admits to Ian that he has completely underestimated her. At the end of the episode, the Doctor reconciles with Barbara, and it is clear that their bond will be much closer from now on. The Doctor has also gained a new respect for Barbara that will most likely lead to him listening to her more often, which will be beneficial for all, since she tends to be right a lot of the time.
The Doctor is continuing to grow as a person with the help of his companions. He has started to become a little less prickly. Especially after this episode, the Doctor trust in Ian and Barbara will be stronger which will allow for them to cultivate a great friendship.
Watch it? Sure. It’s a pretty important episode to the character development of the Doctor, but I wouldn’t consider it pivotal.